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Posted to commits@logging.apache.org by rg...@apache.org on 2021/12/19 06:42:42 UTC

[logging-log4j2] branch log4j-2.12 updated: Fix string substitution recursion (#641)

This is an automated email from the ASF dual-hosted git repository.

rgoers pushed a commit to branch log4j-2.12
in repository https://gitbox.apache.org/repos/asf/logging-log4j2.git


The following commit(s) were added to refs/heads/log4j-2.12 by this push:
     new bf7e916  Fix string substitution recursion (#641)
bf7e916 is described below

commit bf7e916df6335713fe2219c7b3b523fb509deabc
Author: Carter Kozak <ck...@apache.org>
AuthorDate: Sun Dec 19 01:42:37 2021 -0500

    Fix string substitution recursion (#641)
    
    cherry-pick of 806023265f8c905b2dd1d81fd2458f64b2ea0b5e
---
 .../log4j/config/Log4j1ConfigurationParser.java    |   5 +-
 .../apache/logging/log4j/spi/AbstractLogger.java   |  10 +-
 .../log4j/core/config/AbstractConfiguration.java   |  18 +-
 .../logging/log4j/core/config/AppenderControl.java |   4 +-
 .../log4j/core/config/ConfigurationFactory.java    |   3 +-
 .../config/composite/CompositeConfiguration.java   |   2 +-
 .../log4j/core/config/json/JsonConfiguration.java  |   2 +-
 .../core/config/plugins/util/PluginBuilder.java    |  17 +-
 .../log4j/core/config/xml/XmlConfiguration.java    |   2 +-
 .../core/lookup/ConfigurationStrSubstitutor.java   |  63 ++++
 .../log4j/core/lookup/ContextMapLookup.java        |   2 +-
 .../logging/log4j/core/lookup/DateLookup.java      |   2 +-
 .../logging/log4j/core/lookup/Interpolator.java    |   2 +-
 .../log4j/core/lookup/RuntimeStrSubstitutor.java   |  61 ++++
 .../logging/log4j/core/lookup/StrSubstitutor.java  | 342 +++++++++++++++------
 ...rnResolverDoesNotEvaluateThreadContextTest.java | 116 +++++++
 .../RoutingAppenderKeyLookupEvaluationTest.java    |  94 ++++++
 .../log4j/core/lookup/StrSubstitutorTest.java      | 140 ++++++++-
 ...{log4j-routing.xml => log4j-routing-lookup.xml} |  34 +-
 .../src/test/resources/log4j-routing-purge.xml     |   8 +-
 log4j-core/src/test/resources/log4j-routing.json   |   5 +-
 .../src/test/resources/log4j-routing.properties    |   4 +-
 log4j-core/src/test/resources/log4j-routing.xml    |   5 +-
 log4j-core/src/test/resources/log4j-routing2.json  |   5 +-
 .../log4j2-pattern-layout-with-context.xml         |  34 ++
 .../apache/logging/log4j/lookup/CustomLookup.java  |   3 +
 .../logging/log4j/lookup/MapMessageLookup.java     |   3 +
 .../logging/log4j/web/Log4jWebInitializerImpl.java |   3 +-
 src/changes/changes.xml                            |   3 +
 29 files changed, 812 insertions(+), 180 deletions(-)

diff --git a/log4j-1.2-api/src/main/java/org/apache/log4j/config/Log4j1ConfigurationParser.java b/log4j-1.2-api/src/main/java/org/apache/log4j/config/Log4j1ConfigurationParser.java
index 112ab42..3630ce9 100644
--- a/log4j-1.2-api/src/main/java/org/apache/log4j/config/Log4j1ConfigurationParser.java
+++ b/log4j-1.2-api/src/main/java/org/apache/log4j/config/Log4j1ConfigurationParser.java
@@ -39,6 +39,7 @@ import org.apache.logging.log4j.core.config.builder.api.LayoutComponentBuilder;
 import org.apache.logging.log4j.core.config.builder.api.LoggerComponentBuilder;
 import org.apache.logging.log4j.core.config.builder.api.RootLoggerComponentBuilder;
 import org.apache.logging.log4j.core.config.builder.impl.BuiltConfiguration;
+import org.apache.logging.log4j.core.lookup.ConfigurationStrSubstitutor;
 import org.apache.logging.log4j.core.lookup.StrSubstitutor;
 import org.apache.logging.log4j.status.StatusLogger;
 import org.apache.logging.log4j.util.Strings;
@@ -89,8 +90,8 @@ public class Log4j1ConfigurationParser {
             throws IOException {
         try {
             properties.load(input);
-            strSubstitutorProperties = new StrSubstitutor(properties);
-            strSubstitutorSystem = new StrSubstitutor(System.getProperties());
+            strSubstitutorProperties = new ConfigurationStrSubstitutor(properties);
+            strSubstitutorSystem = new ConfigurationStrSubstitutor(System.getProperties());
             final String rootCategoryValue = getLog4jValue(ROOTCATEGORY);
             final String rootLoggerValue = getLog4jValue(ROOTLOGGER);
             if (rootCategoryValue == null && rootLoggerValue == null) {
diff --git a/log4j-api/src/main/java/org/apache/logging/log4j/spi/AbstractLogger.java b/log4j-api/src/main/java/org/apache/logging/log4j/spi/AbstractLogger.java
index 897dcdc..65eff86 100644
--- a/log4j-api/src/main/java/org/apache/logging/log4j/spi/AbstractLogger.java
+++ b/log4j-api/src/main/java/org/apache/logging/log4j/spi/AbstractLogger.java
@@ -2089,8 +2089,8 @@ public abstract class AbstractLogger implements ExtendedLogger, LocationAwareLog
         try {
             incrementRecursionDepth();
             log(level, marker, fqcn, location, message, throwable);
-        } catch (Exception ex) {
-            handleLogMessageException(ex, fqcn, message);
+        } catch (Throwable t) {
+            handleLogMessageException(t, fqcn, message);
         } finally {
             decrementRecursionDepth();
             ReusableMessageFactory.release(message);
@@ -2188,9 +2188,9 @@ public abstract class AbstractLogger implements ExtendedLogger, LocationAwareLog
                                final Throwable throwable) {
         try {
             log(level, marker, fqcn, location, msg, throwable);
-        } catch (final Exception e) {
+        } catch (final Throwable t) {
             // LOG4J2-1990 Log4j2 suppresses all exceptions that occur once application called the logger
-            handleLogMessageException(e, fqcn, msg);
+            handleLogMessageException(t, fqcn, msg);
         }
     }
 
@@ -2203,7 +2203,7 @@ public abstract class AbstractLogger implements ExtendedLogger, LocationAwareLog
 
     // LOG4J2-1990 Log4j2 suppresses all exceptions that occur once application called the logger
     // TODO Configuration setting to propagate exceptions back to the caller *if requested*
-    private void handleLogMessageException(final Exception exception, final String fqcn, final Message msg) {
+    private void handleLogMessageException(final Throwable exception, final String fqcn, final Message msg) {
         if (exception instanceof LoggingException) {
             throw (LoggingException) exception;
         }
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AbstractConfiguration.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AbstractConfiguration.java
index 42e9940..c45d7fc 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AbstractConfiguration.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AbstractConfiguration.java
@@ -54,8 +54,10 @@ import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
 import org.apache.logging.log4j.core.config.plugins.util.PluginType;
 import org.apache.logging.log4j.core.filter.AbstractFilterable;
 import org.apache.logging.log4j.core.layout.PatternLayout;
+import org.apache.logging.log4j.core.lookup.ConfigurationStrSubstitutor;
 import org.apache.logging.log4j.core.lookup.Interpolator;
 import org.apache.logging.log4j.core.lookup.MapLookup;
+import org.apache.logging.log4j.core.lookup.RuntimeStrSubstitutor;
 import org.apache.logging.log4j.core.lookup.StrLookup;
 import org.apache.logging.log4j.core.lookup.StrSubstitutor;
 import org.apache.logging.log4j.core.net.Advertiser;
@@ -127,7 +129,8 @@ public abstract class AbstractConfiguration extends AbstractFilterable implement
     private List<CustomLevelConfig> customLevels = Collections.emptyList();
     private final ConcurrentMap<String, String> propertyMap = new ConcurrentHashMap<>();
     private final StrLookup tempLookup = new Interpolator(propertyMap);
-    private final StrSubstitutor subst = new StrSubstitutor(tempLookup);
+    private final StrSubstitutor subst = new RuntimeStrSubstitutor(tempLookup);
+    private final StrSubstitutor configurationStrSubstitutor = new ConfigurationStrSubstitutor(subst);
     private LoggerConfig root = new LoggerConfig();
     private final ConcurrentMap<String, Object> componentMap = new ConcurrentHashMap<>();
     private final ConfigurationSource configurationSource;
@@ -215,6 +218,7 @@ public abstract class AbstractConfiguration extends AbstractFilterable implement
     public void initialize() {
         LOGGER.debug(Version.getProductString() + " initializing configuration {}", this);
         subst.setConfiguration(this);
+        configurationStrSubstitutor.setConfiguration(this);
         try {
             scriptManager = new ScriptManager(this, watchManager);
         } catch (final LinkageError | Exception e) {
@@ -532,12 +536,16 @@ public abstract class AbstractConfiguration extends AbstractFilterable implement
             final Node first = rootNode.getChildren().get(0);
             createConfiguration(first, null);
             if (first.getObject() != null) {
-                subst.setVariableResolver((StrLookup) first.getObject());
+                StrLookup lookup = (StrLookup) first.getObject();
+                subst.setVariableResolver(lookup);
+                configurationStrSubstitutor.setVariableResolver(lookup);
             }
         } else {
             final Map<String, String> map = this.getComponent(CONTEXT_PROPERTIES);
             final StrLookup lookup = map == null ? null : new MapLookup(map);
-            subst.setVariableResolver(new Interpolator(lookup, pluginPackages));
+            Interpolator interpolator = new Interpolator(lookup, pluginPackages);
+            subst.setVariableResolver(interpolator);
+            configurationStrSubstitutor.setVariableResolver(interpolator);
         }
 
         boolean setLoggers = false;
@@ -714,6 +722,10 @@ public abstract class AbstractConfiguration extends AbstractFilterable implement
         return subst;
     }
 
+    public StrSubstitutor getConfigurationStrSubstitutor() {
+        return configurationStrSubstitutor;
+    }
+
     @Override
     public void setAdvertiser(final Advertiser advertiser) {
         this.advertiser = advertiser;
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AppenderControl.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AppenderControl.java
index 8194ffc..a17b359 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AppenderControl.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/AppenderControl.java
@@ -156,8 +156,8 @@ public class AppenderControl extends AbstractFilterable {
             appender.append(event);
         } catch (final RuntimeException ex) {
             handleAppenderError(event, ex);
-        } catch (final Exception ex) {
-            handleAppenderError(event, new AppenderLoggingException(ex));
+        } catch (final Throwable t) {
+            handleAppenderError(event, new AppenderLoggingException(t));
         }
     }
 
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/ConfigurationFactory.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/ConfigurationFactory.java
index c0f2b23..dd89e81 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/ConfigurationFactory.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/ConfigurationFactory.java
@@ -37,6 +37,7 @@ import org.apache.logging.log4j.core.config.builder.api.ConfigurationBuilderFact
 import org.apache.logging.log4j.core.config.composite.CompositeConfiguration;
 import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
 import org.apache.logging.log4j.core.config.plugins.util.PluginType;
+import org.apache.logging.log4j.core.lookup.ConfigurationStrSubstitutor;
 import org.apache.logging.log4j.core.lookup.Interpolator;
 import org.apache.logging.log4j.core.lookup.StrSubstitutor;
 import org.apache.logging.log4j.core.net.UrlConnectionFactory;
@@ -130,7 +131,7 @@ public abstract class ConfigurationFactory extends ConfigurationBuilderFactory {
 
     private static ConfigurationFactory configFactory = new Factory();
 
-    protected final StrSubstitutor substitutor = new StrSubstitutor(new Interpolator());
+    protected final StrSubstitutor substitutor = new ConfigurationStrSubstitutor(new Interpolator());
 
     private static final Lock LOCK = new ReentrantLock();
 
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/composite/CompositeConfiguration.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/composite/CompositeConfiguration.java
index c4324d0..dc1f180 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/composite/CompositeConfiguration.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/composite/CompositeConfiguration.java
@@ -79,7 +79,7 @@ public class CompositeConfiguration extends AbstractConfiguration implements Rec
                 .withStatus(getDefaultStatus());
         for (final Map.Entry<String, String> entry : rootNode.getAttributes().entrySet()) {
             final String key = entry.getKey();
-            final String value = getStrSubstitutor().replace(entry.getValue());
+            final String value = getConfigurationStrSubstitutor().replace(entry.getValue());
             if ("status".equalsIgnoreCase(key)) {
                 statusConfig.withStatus(value.toUpperCase());
             } else if ("dest".equalsIgnoreCase(key)) {
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/json/JsonConfiguration.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/json/JsonConfiguration.java
index c41a032..3e9dd9c 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/json/JsonConfiguration.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/json/JsonConfiguration.java
@@ -71,7 +71,7 @@ public class JsonConfiguration extends AbstractConfiguration implements Reconfig
             int monitorIntervalSeconds = 0;
             for (final Map.Entry<String, String> entry : rootNode.getAttributes().entrySet()) {
                 final String key = entry.getKey();
-                final String value = getStrSubstitutor().replace(entry.getValue());
+                final String value = getConfigurationStrSubstitutor().replace(entry.getValue());
                 // TODO: this duplicates a lot of the XmlConfiguration constructor
                 if ("status".equalsIgnoreCase(key)) {
                     statusConfig.withStatus(value);
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/plugins/util/PluginBuilder.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/plugins/util/PluginBuilder.java
index f726a3a..0216b24 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/plugins/util/PluginBuilder.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/plugins/util/PluginBuilder.java
@@ -40,6 +40,7 @@ import org.apache.logging.log4j.core.config.plugins.validation.ConstraintValidat
 import org.apache.logging.log4j.core.config.plugins.validation.ConstraintValidators;
 import org.apache.logging.log4j.core.config.plugins.visitors.PluginVisitor;
 import org.apache.logging.log4j.core.config.plugins.visitors.PluginVisitors;
+import org.apache.logging.log4j.core.lookup.ConfigurationStrSubstitutor;
 import org.apache.logging.log4j.core.util.Builder;
 import org.apache.logging.log4j.core.util.ReflectionUtil;
 import org.apache.logging.log4j.core.util.TypeUtil;
@@ -124,20 +125,20 @@ public class PluginBuilder implements Builder<Object> {
         } catch (final ConfigurationException e) { // LOG4J2-1908
             LOGGER.error("Could not create plugin of type {} for element {}", this.clazz, node.getName(), e);
             return null; // no point in trying the factory method
-        } catch (final Exception e) {
+        } catch (final Throwable t) {
             LOGGER.error("Could not create plugin of type {} for element {}: {}",
                     this.clazz, node.getName(),
-                    (e instanceof InvocationTargetException ? ((InvocationTargetException) e).getCause() : e).toString(), e);
+                    (t instanceof InvocationTargetException ? ((InvocationTargetException) t).getCause() : t).toString(), t);
         }
         // or fall back to factory method if no builder class is available
         try {
             final Method factory = findFactoryMethod(this.clazz);
             final Object[] params = generateParameters(factory);
             return factory.invoke(null, params);
-        } catch (final Exception e) {
+        } catch (final Throwable t) {
             LOGGER.error("Unable to invoke factory method in {} for element {}: {}",
                     this.clazz, this.node.getName(),
-                    (e instanceof InvocationTargetException ? ((InvocationTargetException) e).getCause() : e).toString(), e);
+                    (t instanceof InvocationTargetException ? ((InvocationTargetException) t).getCause() : t).toString(), t);
             return null;
         }
     }
@@ -180,7 +181,9 @@ public class PluginBuilder implements Builder<Object> {
                     final Object value = visitor.setAliases(aliases)
                         .setAnnotation(a)
                         .setConversionType(field.getType())
-                        .setStrSubstitutor(configuration.getStrSubstitutor())
+                        .setStrSubstitutor(event == null
+                                ? new ConfigurationStrSubstitutor(configuration.getStrSubstitutor())
+                                : configuration.getStrSubstitutor())
                         .setMember(field)
                         .visit(configuration, node, event, log);
                     // don't overwrite default values if the visitor gives us no value to inject
@@ -253,7 +256,9 @@ public class PluginBuilder implements Builder<Object> {
                     final Object value = visitor.setAliases(aliases)
                         .setAnnotation(a)
                         .setConversionType(types[i])
-                        .setStrSubstitutor(configuration.getStrSubstitutor())
+                        .setStrSubstitutor(event == null
+                                ? new ConfigurationStrSubstitutor(configuration.getStrSubstitutor())
+                                : configuration.getStrSubstitutor())
                         .setMember(factory)
                         .visit(configuration, node, event, log);
                     // don't overwrite existing values if the visitor gives us no value to inject
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
index 6a6c116..939c36c 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/config/xml/XmlConfiguration.java
@@ -110,7 +110,7 @@ public class XmlConfiguration extends AbstractConfiguration implements Reconfigu
             int monitorIntervalSeconds = 0;
             for (final Map.Entry<String, String> entry : attrs.entrySet()) {
                 final String key = entry.getKey();
-                final String value = getStrSubstitutor().replace(entry.getValue());
+                final String value = getConfigurationStrSubstitutor().replace(entry.getValue());
                 if ("status".equalsIgnoreCase(key)) {
                     statusConfig.withStatus(value);
                 } else if ("dest".equalsIgnoreCase(key)) {
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ConfigurationStrSubstitutor.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ConfigurationStrSubstitutor.java
new file mode 100644
index 0000000..1287721
--- /dev/null
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ConfigurationStrSubstitutor.java
@@ -0,0 +1,63 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+package org.apache.logging.log4j.core.lookup;
+
+import java.util.Map;
+import java.util.Properties;
+
+/**
+ * {@link RuntimeStrSubstitutor} is a {@link StrSubstitutor} which only supports recursive evaluation of lookups.
+ * This can be dangerous when combined with user-provided inputs, and should only be used on data directly from
+ * a configuration.
+ */
+public final class ConfigurationStrSubstitutor extends StrSubstitutor {
+
+    public ConfigurationStrSubstitutor() {
+    }
+
+    public ConfigurationStrSubstitutor(final Map<String, String> valueMap) {
+        super(valueMap);
+    }
+
+    public ConfigurationStrSubstitutor(final Properties properties) {
+        super(properties);
+    }
+
+    public ConfigurationStrSubstitutor(final StrLookup lookup) {
+        super(lookup);
+    }
+
+    public ConfigurationStrSubstitutor(final StrSubstitutor other) {
+        super(other);
+    }
+
+    @Override
+    boolean isRecursiveEvaluationAllowed() {
+        return true;
+    }
+
+    @Override
+    void setRecursiveEvaluationAllowed(final boolean recursiveEvaluationAllowed) {
+        throw new UnsupportedOperationException(
+                "recursiveEvaluationAllowed cannot be modified within ConfigurationStrSubstitutor");
+    }
+
+    @Override
+    public String toString() {
+        return "ConfigurationStrSubstitutor{" + super.toString() + "}";
+    }
+}
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ContextMapLookup.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ContextMapLookup.java
index 220d17a..ef60616 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ContextMapLookup.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/ContextMapLookup.java
@@ -55,6 +55,6 @@ public class ContextMapLookup implements StrLookup {
      */
     @Override
     public String lookup(final LogEvent event, final String key) {
-        return event.getContextData().getValue(key);
+        return event == null ? null : event.getContextData().<String>getValue(key);
     }
 }
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/DateLookup.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/DateLookup.java
index 3e630b0..3bcecf7 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/DateLookup.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/DateLookup.java
@@ -54,7 +54,7 @@ public class DateLookup implements StrLookup {
      */
     @Override
     public String lookup(final LogEvent event, final String key) {
-        return formatDate(event.getTimeMillis(), key);
+        return event == null ? lookup(key) : formatDate(event.getTimeMillis(), key);
     }
 
     private String formatDate(final long date, final String format) {
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/Interpolator.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/Interpolator.java
index 01ee511..c8409ab 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/Interpolator.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/Interpolator.java
@@ -47,7 +47,7 @@ public class Interpolator extends AbstractConfigurationAwareLookup {
     private static final Logger LOGGER = StatusLogger.getLogger();
 
     /** Constant for the prefix separator. */
-    private static final char PREFIX_SEPARATOR = ':';
+    static final char PREFIX_SEPARATOR = ':';
 
     private final Map<String, StrLookup> strLookupMap = new HashMap<>();
 
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/RuntimeStrSubstitutor.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/RuntimeStrSubstitutor.java
new file mode 100644
index 0000000..f002c6e
--- /dev/null
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/RuntimeStrSubstitutor.java
@@ -0,0 +1,61 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+package org.apache.logging.log4j.core.lookup;
+
+import java.util.Map;
+import java.util.Properties;
+
+/**
+ * {@link RuntimeStrSubstitutor} is a {@link StrSubstitutor} which only supports evaluation of top-level lookups.
+ */
+public final class RuntimeStrSubstitutor extends StrSubstitutor {
+
+    public RuntimeStrSubstitutor() {
+    }
+
+    public RuntimeStrSubstitutor(final Map<String, String> valueMap) {
+        super(valueMap);
+    }
+
+    public RuntimeStrSubstitutor(final Properties properties) {
+        super(properties);
+    }
+
+    public RuntimeStrSubstitutor(final StrLookup lookup) {
+        super(lookup);
+    }
+
+    public RuntimeStrSubstitutor(final StrSubstitutor other) {
+        super(other);
+    }
+
+    @Override
+    boolean isRecursiveEvaluationAllowed() {
+        return false;
+    }
+
+    @Override
+    void setRecursiveEvaluationAllowed(final boolean recursiveEvaluationAllowed) {
+        throw new UnsupportedOperationException(
+                "recursiveEvaluationAllowed cannot be modified within RuntimeStrSubstitutor");
+    }
+
+    @Override
+    public String toString() {
+        return "RuntimeStrSubstitutor{" + super.toString() + "}";
+    }
+}
diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/StrSubstitutor.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/StrSubstitutor.java
index 405ca28..4818ab0 100644
--- a/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/StrSubstitutor.java
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/lookup/StrSubstitutor.java
@@ -22,11 +22,13 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Properties;
 
 import org.apache.logging.log4j.core.LogEvent;
 import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.config.ConfigurationAware;
+import org.apache.logging.log4j.status.StatusLogger;
 import org.apache.logging.log4j.util.Strings;
 
 /**
@@ -158,7 +160,11 @@ public class StrSubstitutor implements ConfigurationAware {
     /**
      * Constant for the default value delimiter of a variable.
      */
-    public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(":-");
+    public static final String DEFAULT_VALUE_DELIMITER_STRING = ":-";
+    public static final StrMatcher DEFAULT_VALUE_DELIMITER = StrMatcher.stringMatcher(DEFAULT_VALUE_DELIMITER_STRING);
+
+    public static final String ESCAPE_DELIMITER_STRING = ":\\-";
+    public static final StrMatcher DEFAULT_VALUE_ESCAPE_DELIMITER = StrMatcher.stringMatcher(ESCAPE_DELIMITER_STRING);
 
     private static final int BUF_SIZE = 256;
 
@@ -180,9 +186,15 @@ public class StrSubstitutor implements ConfigurationAware {
     /**
      * Stores the default variable value delimiter
      */
+    private String valueDelimiterString;
     private StrMatcher valueDelimiterMatcher;
 
     /**
+     * Escape string to avoid matching the value delimiter matcher;
+     */
+    private StrMatcher valueEscapeDelimiterMatcher;
+
+    /**
      * Variable resolution is delegated to an implementer of VariableResolver.
      */
     private StrLookup variableResolver;
@@ -197,6 +209,8 @@ public class StrSubstitutor implements ConfigurationAware {
      */
     private Configuration configuration;
 
+    private boolean recursiveEvaluationAllowed;
+
     //-----------------------------------------------------------------------
     /**
      * Creates a new instance with defaults for variable prefix and suffix
@@ -323,7 +337,9 @@ public class StrSubstitutor implements ConfigurationAware {
     public StrSubstitutor(final StrLookup variableResolver, final StrMatcher prefixMatcher,
                           final StrMatcher suffixMatcher,
                           final char escape) {
-        this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER);
+        this(variableResolver, prefixMatcher, suffixMatcher, escape, DEFAULT_VALUE_DELIMITER,
+                DEFAULT_VALUE_ESCAPE_DELIMITER);
+        this.valueDelimiterString = DEFAULT_VALUE_DELIMITER_STRING;
     }
 
     /**
@@ -336,8 +352,8 @@ public class StrSubstitutor implements ConfigurationAware {
      * @param valueDelimiterMatcher  the variable default value delimiter matcher, may be null
      * @throws IllegalArgumentException if the prefix or suffix is null
      */
-    public StrSubstitutor(
-            final StrLookup variableResolver, final StrMatcher prefixMatcher, final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher) {
+    public StrSubstitutor(final StrLookup variableResolver, final StrMatcher prefixMatcher,
+            final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher) {
         this.setVariableResolver(variableResolver);
         this.setVariablePrefixMatcher(prefixMatcher);
         this.setVariableSuffixMatcher(suffixMatcher);
@@ -345,6 +361,42 @@ public class StrSubstitutor implements ConfigurationAware {
         this.setValueDelimiterMatcher(valueDelimiterMatcher);
     }
 
+    /**
+     * Creates a new instance and initializes it.
+     *
+     * @param variableResolver  the variable resolver, may be null
+     * @param prefixMatcher  the prefix for variables, not null
+     * @param suffixMatcher  the suffix for variables, not null
+     * @param escape  the escape character
+     * @param valueDelimiterMatcher  the variable default value delimiter matcher, may be null
+     * @param valueEscapeMatcher the matcher to escape defaulting, may be null.
+     * @throws IllegalArgumentException if the prefix or suffix is null
+     */
+    public StrSubstitutor(final StrLookup variableResolver, final StrMatcher prefixMatcher,
+                          final StrMatcher suffixMatcher, final char escape, final StrMatcher valueDelimiterMatcher,
+                          final StrMatcher valueEscapeMatcher) {
+        this.setVariableResolver(variableResolver);
+        this.setVariablePrefixMatcher(prefixMatcher);
+        this.setVariableSuffixMatcher(suffixMatcher);
+        this.setEscapeChar(escape);
+        this.setValueDelimiterMatcher(valueDelimiterMatcher);
+        valueEscapeDelimiterMatcher = valueEscapeMatcher;
+    }
+
+    StrSubstitutor(final StrSubstitutor other) {
+        Objects.requireNonNull(other, "other");
+        this.setVariableResolver(other.getVariableResolver());
+        this.setVariablePrefixMatcher(other.getVariablePrefixMatcher());
+        this.setVariableSuffixMatcher(other.getVariableSuffixMatcher());
+        this.setEscapeChar(other.getEscapeChar());
+        this.setValueDelimiterMatcher(other.valueDelimiterMatcher);
+        this.valueEscapeDelimiterMatcher = other.valueEscapeDelimiterMatcher;
+        this.configuration = other.configuration;
+        this.recursiveEvaluationAllowed = other.isRecursiveEvaluationAllowed();
+        this.enableSubstitutionInVariables = other.isEnableSubstitutionInVariables();
+        this.valueDelimiterString = other.valueDelimiterString;
+    }
+
     //-----------------------------------------------------------------------
     /**
      * Replaces all the occurrences of variables in the given source object with
@@ -405,6 +457,11 @@ public class StrSubstitutor implements ConfigurationAware {
         return map;
     }
 
+    private static String handleFailedReplacement(String input, Throwable throwable) {
+        StatusLogger.getLogger().error("Replacement failed on {}", input, throwable);
+        return input;
+    }
+
     //-----------------------------------------------------------------------
     /**
      * Replaces all the occurrences of variables with their matching values
@@ -430,8 +487,12 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(source);
-        if (!substitute(event, buf, 0, source.length())) {
-            return source;
+        try {
+            if (!substitute(event, buf, 0, source.length())) {
+                return source;
+            }
+        } catch (Throwable t) {
+            return handleFailedReplacement(source, t);
         }
         return buf.toString();
     }
@@ -472,8 +533,12 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
-        if (!substitute(event, buf, 0, length)) {
-            return source.substring(offset, offset + length);
+        try {
+            if (!substitute(event, buf, 0, length)) {
+                return source.substring(offset, offset + length);
+            }
+        } catch (Throwable t) {
+            return handleFailedReplacement(source, t);
         }
         return buf.toString();
     }
@@ -506,7 +571,11 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(source.length).append(source);
-        substitute(event, buf, 0, source.length);
+        try {
+            substitute(event, buf, 0, source.length);
+        } catch (Throwable t) {
+            return handleFailedReplacement(new String(source), t);
+        }
         return buf.toString();
     }
 
@@ -548,7 +617,11 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
-        substitute(event, buf, 0, length);
+        try {
+            substitute(event, buf, 0, length);
+        } catch (Throwable t) {
+            return handleFailedReplacement(new String(source, offset, length), t);
+        }
         return buf.toString();
     }
 
@@ -580,7 +653,11 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(source.length()).append(source);
-        substitute(event, buf, 0, buf.length());
+        try {
+            substitute(event, buf, 0, buf.length());
+        } catch (Throwable t) {
+            return handleFailedReplacement(source.toString(), t);
+        }
         return buf.toString();
     }
 
@@ -622,7 +699,11 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
-        substitute(event, buf, 0, length);
+        try {
+            substitute(event, buf, 0, length);
+        } catch (Throwable t) {
+            return handleFailedReplacement(source.substring(offset, offset + length), t);
+        }
         return buf.toString();
     }
 
@@ -654,7 +735,11 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(source.length()).append(source);
-        substitute(event, buf, 0, buf.length());
+        try {
+            substitute(event, buf, 0, buf.length());
+        } catch (Throwable t) {
+            return handleFailedReplacement(source.toString(), t);
+        }
         return buf.toString();
     }
     /**
@@ -695,7 +780,11 @@ public class StrSubstitutor implements ConfigurationAware {
             return null;
         }
         final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
-        substitute(event, buf, 0, length);
+        try {
+            substitute(event, buf, 0, length);
+        } catch (Throwable t) {
+            return handleFailedReplacement(source.substring(offset, offset + length), t);
+        }
         return buf.toString();
     }
 
@@ -725,8 +814,13 @@ public class StrSubstitutor implements ConfigurationAware {
         if (source == null) {
             return null;
         }
-        final StringBuilder buf = new StringBuilder().append(source);
-        substitute(event, buf, 0, buf.length());
+        String stringValue = String.valueOf(source);
+        final StringBuilder buf = new StringBuilder(stringValue.length()).append(stringValue);
+        try {
+            substitute(event, buf, 0, buf.length());
+        } catch (Throwable t) {
+            return handleFailedReplacement(stringValue, t);
+        }
         return buf.toString();
     }
 
@@ -784,7 +878,12 @@ public class StrSubstitutor implements ConfigurationAware {
             return false;
         }
         final StringBuilder buf = new StringBuilder(length).append(source, offset, length);
-        if (!substitute(event, buf, 0, length)) {
+        try {
+            if (!substitute(event, buf, 0, length)) {
+                return false;
+            }
+        } catch (Throwable t) {
+            StatusLogger.getLogger().error("Replacement failed on {}", source, t);
             return false;
         }
         source.replace(offset, offset + length, buf.toString());
@@ -909,100 +1008,123 @@ public class StrSubstitutor implements ConfigurationAware {
             final int startMatchLen = prefixMatcher.isMatch(chars, pos, offset, bufEnd);
             if (startMatchLen == 0) {
                 pos++;
+            } else // found variable start marker
+            if (pos > offset && chars[pos - 1] == escape) {
+                // escaped
+                buf.deleteCharAt(pos - 1);
+                chars = getChars(buf);
+                lengthChange--;
+                altered = true;
+                bufEnd--;
             } else {
-                // found variable start marker
-                if (pos > offset && chars[pos - 1] == escape) {
-                    // escaped
-                    buf.deleteCharAt(pos - 1);
-                    chars = getChars(buf);
-                    lengthChange--;
-                    altered = true;
-                    bufEnd--;
-                } else {
-                    // find suffix
-                    final int startPos = pos;
-                    pos += startMatchLen;
-                    int endMatchLen = 0;
-                    int nestedVarCount = 0;
-                    while (pos < bufEnd) {
-                        if (substitutionInVariablesEnabled
-                                && (endMatchLen = prefixMatcher.isMatch(chars, pos, offset, bufEnd)) != 0) {
-                            // found a nested variable start
-                            nestedVarCount++;
-                            pos += endMatchLen;
-                            continue;
-                        }
+                // find suffix
+                final int startPos = pos;
+                pos += startMatchLen;
+                int endMatchLen = 0;
+                int nestedVarCount = 0;
+                while (pos < bufEnd) {
+                    if (substitutionInVariablesEnabled
+                            && (endMatchLen = prefixMatcher.isMatch(chars, pos, offset, bufEnd)) != 0) {
+                        // found a nested variable start
+                        nestedVarCount++;
+                        pos += endMatchLen;
+                        continue;
+                    }
 
-                        endMatchLen = suffixMatcher.isMatch(chars, pos, offset, bufEnd);
-                        if (endMatchLen == 0) {
-                            pos++;
-                        } else {
-                            // found variable end marker
-                            if (nestedVarCount == 0) {
-                                String varNameExpr = new String(chars, startPos + startMatchLen, pos - startPos - startMatchLen);
-                                if (substitutionInVariablesEnabled) {
-                                    final StringBuilder bufName = new StringBuilder(varNameExpr);
-                                    substitute(event, bufName, 0, bufName.length());
-                                    varNameExpr = bufName.toString();
+                    endMatchLen = suffixMatcher.isMatch(chars, pos, offset, bufEnd);
+                    if (endMatchLen == 0) {
+                        pos++;
+                    } else {
+                        // found variable end marker
+                        if (nestedVarCount == 0) {
+                            String varNameExpr = new String(chars, startPos + startMatchLen, pos - startPos - startMatchLen);
+                            if (substitutionInVariablesEnabled) {
+                                // initialize priorVariables if they're not already set
+                                if (priorVariables == null) {
+                                    priorVariables = new ArrayList<>();
                                 }
-                                pos += endMatchLen;
-                                final int endPos = pos;
-
-                                String varName = varNameExpr;
-                                String varDefaultValue = null;
-
-                                if (valueDelimiterMatcher != null) {
-                                    final char [] varNameExprChars = varNameExpr.toCharArray();
-                                    int valueDelimiterMatchLen = 0;
-                                    for (int i = 0; i < varNameExprChars.length; i++) {
-                                        // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
-                                        if (!substitutionInVariablesEnabled
-                                                && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
+                                final StringBuilder bufName = new StringBuilder(varNameExpr);
+                                substitute(event, bufName, 0, bufName.length(), priorVariables);
+                                varNameExpr = bufName.toString();
+                            }
+                            pos += endMatchLen;
+                            final int endPos = pos;
+
+                            String varName = varNameExpr;
+                            String varDefaultValue = null;
+
+                            if (valueDelimiterMatcher != null) {
+                                final char [] varNameExprChars = varNameExpr.toCharArray();
+                                int valueDelimiterMatchLen = 0;
+                                for (int i = 0; i < varNameExprChars.length; i++) {
+                                    // if there's any nested variable when nested variable substitution disabled, then stop resolving name and default value.
+                                    if (!substitutionInVariablesEnabled
+                                            && prefixMatcher.isMatch(varNameExprChars, i, i, varNameExprChars.length) != 0) {
+                                        break;
+                                    }
+                                    if (valueEscapeDelimiterMatcher != null) {
+                                        int matchLen = valueEscapeDelimiterMatcher.isMatch(varNameExprChars, i);
+                                        if (matchLen != 0) {
+                                            String varNamePrefix = varNameExpr.substring(0, i) + Interpolator.PREFIX_SEPARATOR;
+                                            varName = varNamePrefix + varNameExpr.substring(i + matchLen - 1);
+                                            for (int j = i + matchLen; j < varNameExprChars.length; ++j){
+                                                if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, j)) != 0) {
+                                                    varName = varNamePrefix + varNameExpr.substring(i + matchLen, j);
+                                                    varDefaultValue = varNameExpr.substring(j + valueDelimiterMatchLen);
+                                                    break;
+                                                }
+                                            }
                                             break;
-                                        }
-                                        if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, i)) != 0) {
+                                        } else if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, i)) != 0) {
                                             varName = varNameExpr.substring(0, i);
                                             varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
                                             break;
                                         }
+                                    } else if ((valueDelimiterMatchLen = valueDelimiterMatcher.isMatch(varNameExprChars, i)) != 0) {
+                                        varName = varNameExpr.substring(0, i);
+                                        varDefaultValue = varNameExpr.substring(i + valueDelimiterMatchLen);
+                                        break;
                                     }
                                 }
+                            }
 
-                                // on the first call initialize priorVariables
-                                if (priorVariables == null) {
-                                    priorVariables = new ArrayList<>();
-                                    priorVariables.add(new String(chars, offset, length + lengthChange));
-                                }
+                            // on the first call initialize priorVariables
+                            if (priorVariables == null) {
+                                priorVariables = new ArrayList<>();
+                                priorVariables.add(new String(chars, offset, length + lengthChange));
+                            }
 
-                                // handle cyclic substitution
-                                checkCyclicSubstitution(varName, priorVariables);
-                                priorVariables.add(varName);
+                            // handle cyclic substitution
+                            boolean isCyclic = isCyclicSubstitution(varName, priorVariables);
 
-                                // resolve the variable
-                                String varValue = resolveVariable(event, varName, buf, startPos, endPos);
-                                if (varValue == null) {
-                                    varValue = varDefaultValue;
-                                }
-                                if (varValue != null) {
-                                    // recursive replace
-                                    final int varLen = varValue.length();
-                                    buf.replace(startPos, endPos, varValue);
-                                    altered = true;
-                                    int change = substitute(event, buf, startPos, varLen, priorVariables);
-                                    change = change + (varLen - (endPos - startPos));
-                                    pos += change;
-                                    bufEnd += change;
-                                    lengthChange += change;
-                                    chars = getChars(buf); // in case buffer was altered
-                                }
+                            // resolve the variable
+                            String varValue = isCyclic ? null : resolveVariable(event, varName, buf, startPos, endPos);
+                            if (varValue == null) {
+                                varValue = varDefaultValue;
+                            }
+                            if (varValue != null) {
+                                // recursive replace
+                                final int varLen = varValue.length();
+                                buf.replace(startPos, endPos, varValue);
+                                altered = true;
+                                int change = isRecursiveEvaluationAllowed()
+                                        ? substitute(event, buf, startPos, varLen, priorVariables)
+                                        : 0;
+                                change = change + (varLen - (endPos - startPos));
+                                pos += change;
+                                bufEnd += change;
+                                lengthChange += change;
+                                chars = getChars(buf); // in case buffer was altered
+                            }
 
-                                // remove variable from the cyclic stack
+                            // remove variable from the cyclic stack
+                            if (!isCyclic) {
                                 priorVariables.remove(priorVariables.size() - 1);
-                                break;
                             }
-                            nestedVarCount--;
-                            pos += endMatchLen;
+                            break;
                         }
+                        nestedVarCount--;
+                        pos += endMatchLen;
                     }
                 }
             }
@@ -1014,21 +1136,23 @@ public class StrSubstitutor implements ConfigurationAware {
     }
 
     /**
-     * Checks if the specified variable is already in the stack (list) of variables.
+     * Checks if the specified variable is already in the stack (list) of variables, adding the value
+     * if it's not already present.
      *
      * @param varName  the variable name to check
      * @param priorVariables  the list of prior variables
+     * @return true if this is a cyclic substitution
      */
-    private void checkCyclicSubstitution(final String varName, final List<String> priorVariables) {
+    private boolean isCyclicSubstitution(final String varName, final List<String> priorVariables) {
         if (!priorVariables.contains(varName)) {
-            return;
+            priorVariables.add(varName);
+            return false;
         }
         final StringBuilder buf = new StringBuilder(BUF_SIZE);
         buf.append("Infinite loop in property interpolation of ");
-        buf.append(priorVariables.remove(0));
-        buf.append(": ");
         appendWithSeparators(buf, priorVariables, "->");
-        throw new IllegalStateException(buf.toString());
+        StatusLogger.getLogger().warn(buf);
+        return true;
     }
 
     /**
@@ -1057,7 +1181,12 @@ public class StrSubstitutor implements ConfigurationAware {
         if (resolver == null) {
             return null;
         }
-        return resolver.lookup(event, variableName);
+        try {
+            return resolver.lookup(event, variableName);
+        } catch (Throwable t) {
+            StatusLogger.getLogger().error("Resolver failed to lookup {}", variableName, t);
+            return null;
+        }
     }
 
     // Escape
@@ -1294,6 +1423,9 @@ public class StrSubstitutor implements ConfigurationAware {
             setValueDelimiterMatcher(null);
             return this;
         }
+        String escapeValue = valueDelimiter.substring(0, valueDelimiter.length() - 1) + "\\"
+                + valueDelimiter.substring(valueDelimiter.length() - 1);
+        valueEscapeDelimiterMatcher = StrMatcher.stringMatcher(escapeValue);
         return setValueDelimiterMatcher(StrMatcher.stringMatcher(valueDelimiter));
     }
 
@@ -1343,6 +1475,14 @@ public class StrSubstitutor implements ConfigurationAware {
         this.enableSubstitutionInVariables = enableSubstitutionInVariables;
     }
 
+    boolean isRecursiveEvaluationAllowed() {
+        return recursiveEvaluationAllowed;
+    }
+
+    void setRecursiveEvaluationAllowed(final boolean recursiveEvaluationAllowed) {
+        this.recursiveEvaluationAllowed = recursiveEvaluationAllowed;
+    }
+
     private char[] getChars(final StringBuilder sb) {
         final char[] chars = new char[sb.length()];
         sb.getChars(0, sb.length(), chars, 0);
diff --git a/log4j-core/src/test/java/org/apache/logging/log4j/core/PatternResolverDoesNotEvaluateThreadContextTest.java b/log4j-core/src/test/java/org/apache/logging/log4j/core/PatternResolverDoesNotEvaluateThreadContextTest.java
new file mode 100644
index 0000000..fc65e14
--- /dev/null
+++ b/log4j-core/src/test/java/org/apache/logging/log4j/core/PatternResolverDoesNotEvaluateThreadContextTest.java
@@ -0,0 +1,116 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+package org.apache.logging.log4j.core;
+
+import org.apache.logging.log4j.ThreadContext;
+import org.apache.logging.log4j.junit.LoggerContextRule;
+import org.apache.logging.log4j.test.appender.ListAppender;
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertEquals;
+
+public class PatternResolverDoesNotEvaluateThreadContextTest {
+
+
+    private static final String CONFIG = "log4j2-pattern-layout-with-context.xml";
+    private static final String PARAMETER = "user";
+    private ListAppender listAppender;
+
+    @ClassRule
+    public static LoggerContextRule context = new LoggerContextRule(CONFIG);
+
+    @Before
+    public void before() {
+        listAppender = context.getRequiredAppender("list", ListAppender.class);
+        listAppender.clear();
+    }
+
+    @Test
+    public void testNoUserSet() {
+        Logger logger = context.getLogger(getClass());
+        logger.info("This is a test");
+        List<String> messages = listAppender.getMessages();
+        assertTrue("No messages returned", messages != null && messages.size() > 0);
+        String message = messages.get(0);
+        assertEquals("INFO org.apache.logging.log4j.core." +
+                "PatternResolverDoesNotEvaluateThreadContextTest ${ctx:user} This is a test", message);
+    }
+
+    @Test
+    public void testMessageIsNotLookedUp() {
+        Logger logger = context.getLogger(getClass());
+        logger.info("This is a ${upper:test}");
+        List<String> messages = listAppender.getMessages();
+        assertTrue("No messages returned", messages != null && messages.size() > 0);
+        String message = messages.get(0);
+        assertEquals("INFO org.apache.logging.log4j.core." +
+                "PatternResolverDoesNotEvaluateThreadContextTest ${ctx:user} This is a ${upper:test}", message);
+    }
+
+    @Test
+    public void testUser() {
+        Logger logger = context.getLogger(getClass());
+        ThreadContext.put(PARAMETER, "123");
+        try {
+            logger.info("This is a test");
+        } finally {
+            ThreadContext.remove(PARAMETER);
+        }
+        List<String> messages = listAppender.getMessages();
+        assertTrue("No messages returned", messages != null && messages.size() > 0);
+        String message = messages.get(0);
+        assertEquals("INFO org.apache.logging.log4j.core." +
+                "PatternResolverDoesNotEvaluateThreadContextTest 123 This is a test", message);
+    }
+
+    @Test
+    public void testUserIsLookup() {
+        Logger logger = context.getLogger(getClass());
+        ThreadContext.put(PARAMETER, "${java:version}");
+        try {
+            logger.info("This is a test");
+        } finally {
+            ThreadContext.remove(PARAMETER);
+        }
+        List<String> messages = listAppender.getMessages();
+        assertTrue("No messages returned", messages != null && messages.size() > 0);
+        String message = messages.get(0);
+        assertEquals("INFO org.apache.logging.log4j.core." +
+                "PatternResolverDoesNotEvaluateThreadContextTest ${java:version} This is a test", message);
+    }
+
+    @Test
+    public void testUserHasLookup() {
+        Logger logger = context.getLogger(getClass());
+        ThreadContext.put(PARAMETER, "user${java:version}name");
+        try {
+            logger.info("This is a test");
+        } finally {
+            ThreadContext.remove(PARAMETER);
+        }
+        List<String> messages = listAppender.getMessages();
+        assertTrue("No messages returned",messages != null && messages.size() > 0);
+        String message = messages.get(0);
+        assertEquals("INFO org.apache.logging.log4j.core." +
+                "PatternResolverDoesNotEvaluateThreadContextTest user${java:version}name This is a test", message);
+    }
+}
diff --git a/log4j-core/src/test/java/org/apache/logging/log4j/core/appender/routing/RoutingAppenderKeyLookupEvaluationTest.java b/log4j-core/src/test/java/org/apache/logging/log4j/core/appender/routing/RoutingAppenderKeyLookupEvaluationTest.java
new file mode 100644
index 0000000..963240f
--- /dev/null
+++ b/log4j-core/src/test/java/org/apache/logging/log4j/core/appender/routing/RoutingAppenderKeyLookupEvaluationTest.java
@@ -0,0 +1,94 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+package org.apache.logging.log4j.core.appender.routing;
+
+import org.apache.logging.log4j.ThreadContext;
+import org.apache.logging.log4j.core.Logger;
+import org.apache.logging.log4j.junit.LoggerContextRule;
+import org.apache.logging.log4j.test.appender.ListAppender;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class RoutingAppenderKeyLookupEvaluationTest {
+    private static final String CONFIG = "log4j-routing-lookup.xml";
+
+    private static final String KEY = "user";
+    private ListAppender app;
+
+    @Rule
+    public final LoggerContextRule loggerContextRule = new LoggerContextRule(CONFIG);
+
+    @Before
+    public void setUp() throws Exception {
+        ThreadContext.remove(KEY);
+        this.app = this.loggerContextRule.getListAppender("List");
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        this.app.clear();
+        this.loggerContextRule.getLoggerContext().stop();
+        ThreadContext.remove(KEY);
+    }
+
+    @Test
+    public void testRoutingNoUser() {
+        Logger logger = loggerContextRule.getLogger(getClass());
+        logger.warn("no user");
+        String message = app.getMessages().get(0);
+        assertEquals("WARN ${ctx:user} no user", message);
+    }
+
+    @Test
+    public void testRoutingDoesNotMatchRoute() {
+        Logger logger = loggerContextRule.getLogger(getClass());
+        ThreadContext.put(KEY, "noRouteExists");
+        logger.warn("unmatched user");
+        assertTrue(app.getMessages().isEmpty());
+    }
+
+    @Test
+    public void testRoutingContainsLookup() {
+        Logger logger = loggerContextRule.getLogger(getClass());
+        ThreadContext.put(KEY, "${java:version}");
+        logger.warn("naughty user");
+        String message = app.getMessages().get(0);
+        assertEquals("WARN ${java:version} naughty user", message);
+    }
+
+    @Test
+    public void testRoutingMatchesEscapedLookup() {
+        Logger logger = loggerContextRule.getLogger(getClass());
+        ThreadContext.put(KEY, "${upper:name}");
+        logger.warn("naughty user");
+        String message = app.getMessages().get(0);
+        assertEquals("WARN ${upper:name} naughty user", message);
+    }
+
+    @Test
+    public void testRoutesThemselvesNotEvaluated() {
+        Logger logger = loggerContextRule.getLogger(getClass());
+        ThreadContext.put(KEY, "NAME");
+        logger.warn("unmatched user");
+        assertTrue(app.getMessages().isEmpty());
+    }
+}
diff --git a/log4j-core/src/test/java/org/apache/logging/log4j/core/lookup/StrSubstitutorTest.java b/log4j-core/src/test/java/org/apache/logging/log4j/core/lookup/StrSubstitutorTest.java
index 41b7979..afb3bdd 100644
--- a/log4j-core/src/test/java/org/apache/logging/log4j/core/lookup/StrSubstitutorTest.java
+++ b/log4j-core/src/test/java/org/apache/logging/log4j/core/lookup/StrSubstitutorTest.java
@@ -20,15 +20,13 @@ import java.util.HashMap;
 import java.util.Map;
 
 import org.apache.logging.log4j.ThreadContext;
+import org.apache.logging.log4j.core.LogEvent;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
 
-/**
- *
- */
 public class StrSubstitutorTest {
 
     private static final String TESTKEY = "TestKey";
@@ -48,7 +46,7 @@ public class StrSubstitutorTest {
 
     @Test
     public void testLookup() {
-        final Map<String, String> map = new HashMap<>();
+        final Map<String, String> map = new HashMap<String, String>();
         map.put(TESTKEY, TESTVAL);
         final StrLookup lookup = new Interpolator(new MapLookup(map));
         final StrSubstitutor subst = new StrSubstitutor(lookup);
@@ -68,7 +66,7 @@ public class StrSubstitutorTest {
 
     @Test
     public void testDefault() {
-        final Map<String, String> map = new HashMap<>();
+        final Map<String, String> map = new HashMap<String, String>();
         map.put(TESTKEY, TESTVAL);
         final StrLookup lookup = new Interpolator(new MapLookup(map));
         final StrSubstitutor subst = new StrSubstitutor(lookup);
@@ -77,4 +75,136 @@ public class StrSubstitutorTest {
         final String value = subst.replace("${sys:TestKey1:-${ctx:TestKey}}");
         assertEquals("TestValue", value);
     }
+
+    @Test
+    public void testDefaultReferencesLookupValue() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put(TESTKEY, "${java:version}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(false);
+        final String value = subst.replace("${sys:TestKey1:-${ctx:TestKey}}");
+        assertEquals("${java:version}", value);
+    }
+
+    @Test
+    public void testInfiniteSubstitutionOnString() {
+        final StrLookup lookup = new Interpolator(new MapLookup(new HashMap<String, String>()));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        String infiniteSubstitution = "${${::-${::-$${::-j}}}}";
+        assertEquals(infiniteSubstitution, subst.replace(infiniteSubstitution));
+    }
+
+    @Test
+    public void testInfiniteSubstitutionOnStringBuilder() {
+        final StrLookup lookup = new Interpolator(new MapLookup(new HashMap<String, String>()));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        String infiniteSubstitution = "${${::-${::-$${::-j}}}}";
+        assertEquals(infiniteSubstitution, subst.replace(null, new StringBuilder(infiniteSubstitution)));
+    }
+
+    @Test
+    public void testRecursiveSubstitution() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${ctx:first}");
+        map.put("second", "secondValue");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        assertEquals("${ctx:first} and secondValue", subst.replace("${ctx:first} and ${ctx:second}"));
+    }
+
+    @Test
+    public void testRecursiveWithDefault() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${ctx:first:-default}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        assertEquals("default", subst.replace("${ctx:first}"));
+    }
+
+    @Test
+    public void testRecursiveWithRecursiveDefault() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${ctx:first:-${ctx:first}}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        assertEquals("${ctx:first}", subst.replace("${ctx:first}"));
+    }
+
+    @Test
+    public void testNestedSelfReferenceWithRecursiveEvaluation() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${${ctx:first}}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        assertEquals("${${ctx:first}}", subst.replace("${ctx:first}"));
+    }
+
+    @Test
+    public void testRandomWithRecursiveDefault() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${env:RANDOM:-${ctx:first}}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(true);
+        assertEquals("${ctx:first}", subst.replace("${ctx:first}"));
+    }
+
+    @Test
+    public void testNoRecursiveEvaluationWithDefault() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${java:version}");
+        map.put("second", "${java:runtime}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(false);
+        assertEquals("${java:version}", subst.replace("${ctx:first:-${ctx:second}}"));
+    }
+
+    @Test
+    public void testNoRecursiveEvaluationWithDepthOne() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${java:version}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(false);
+        assertEquals("${java:version}", subst.replace("${ctx:first}"));
+    }
+
+    @Test
+    public void testLookupsNestedWithoutRecursiveEvaluation() {
+        final Map<String, String> map = new HashMap<String, String>();
+        map.put("first", "${java:version}");
+        final StrLookup lookup = new Interpolator(new MapLookup(map));
+        final StrSubstitutor subst = new StrSubstitutor(lookup);
+        subst.setRecursiveEvaluationAllowed(false);
+        assertEquals("${java:version}", subst.replace("${${lower:C}t${lower:X}:first}"));
+    }
+
+    @Test
+    public void testLookupThrows() {
+        final StrSubstitutor subst = new StrSubstitutor(new Interpolator(new StrLookup() {
+
+            @Override
+            public String lookup(String key) {
+                if ("throw".equals(key)) {
+                    throw new RuntimeException();
+                }
+                return "success";
+            }
+
+            @Override
+            public String lookup(LogEvent event, String key) {
+                return lookup(key);
+            }
+        }));
+        subst.setRecursiveEvaluationAllowed(false);
+        assertEquals("success ${foo:throw} success", subst.replace("${foo:a} ${foo:throw} ${foo:c}"));
+    }
 }
diff --git a/log4j-core/src/test/resources/log4j-routing.xml b/log4j-core/src/test/resources/log4j-routing-lookup.xml
similarity index 51%
copy from log4j-core/src/test/resources/log4j-routing.xml
copy to log4j-core/src/test/resources/log4j-routing-lookup.xml
index 4d83886..92f31c3 100644
--- a/log4j-core/src/test/resources/log4j-routing.xml
+++ b/log4j-core/src/test/resources/log4j-routing-lookup.xml
@@ -16,43 +16,23 @@
  limitations under the License.
 
 -->
-<Configuration status="OFF" name="RoutingTest">
-  <Properties>
-    <Property name="filename">target/routing1/routingtest-$${sd:type}.log</Property>
-  </Properties>
-  <ThresholdFilter level="debug"/>
-
+<Configuration status="OFF" name="RoutingAppenderKeyLookupEvaluationTest">
   <Appenders>
-    <Console name="STDOUT">
-      <PatternLayout pattern="%m%n"/>
-    </Console>
     <List name="List">
-      <ThresholdFilter level="debug"/>
+      <PatternLayout pattern="%p $${ctx:user} $${event:Message}"/>
     </List>
     <Routing name="Routing">
-      <Routes pattern="$${sd:type}">
-        <Route>
-          <RollingFile name="Routing-${sd:type}" fileName="${filename}"
-                       filePattern="target/routing1/test1-${sd:type}.%i.log.gz">
-            <PatternLayout>
-              <Pattern>%d %p %C{1.} [%t] %m%n</Pattern>
-            </PatternLayout>
-            <SizeBasedTriggeringPolicy size="500" />
-          </RollingFile>
-        </Route>
-        <Route ref="STDOUT" key="Audit"/>
-        <Route ref="List" key="Service"/>
+      <Routes pattern="$${ctx:user:-none}">
+        <Route ref="List" key="$${upper:name}"/>
+        <Route ref="List" key="none"/>
+        <Route ref="List" key="$${java:version}"/>
       </Routes>
     </Routing>
   </Appenders>
 
   <Loggers>
-    <Logger name="EventLogger" level="info" additivity="false">
+    <Root level="debug">
       <AppenderRef ref="Routing"/>
-    </Logger>
-
-    <Root level="error">
-      <AppenderRef ref="STDOUT"/>
     </Root>
   </Loggers>
 
diff --git a/log4j-core/src/test/resources/log4j-routing-purge.xml b/log4j-core/src/test/resources/log4j-routing-purge.xml
index d1de288..910ba80 100644
--- a/log4j-core/src/test/resources/log4j-routing-purge.xml
+++ b/log4j-core/src/test/resources/log4j-routing-purge.xml
@@ -17,10 +17,6 @@
 
 -->
 <Configuration status="OFF" name="RoutingTest">
-  <Properties>
-    <Property name="filename-idle">target/routing-purge-idle/routingtest-$${sd:id}.log</Property>
-    <Property name="filename-manual">target/routing-purge-manual/routingtest-$${sd:id}.log</Property>
-  </Properties>
   <ThresholdFilter level="debug"/>
 
   <Appenders>
@@ -34,7 +30,7 @@
     <Routing name="RoutingPurgeIdle">
       <Routes pattern="$${sd:id}">
         <Route>
-          <File name="Routing-${sd:id}" fileName="${filename-idle}">
+          <File name="Routing-${sd:id}" fileName="target/routing-purge-idle/routingtest-${sd:id}.log">
             <PatternLayout>
               <Pattern>%d %p %C{1.} [%t] %m%n</Pattern>
             </PatternLayout>
@@ -58,7 +54,7 @@
     <Routing name="RoutingPurgeManual">
       <Routes pattern="$${sd:id}">
         <Route>
-          <File name="Routing-${sd:id}" fileName="${filename-manual}">
+          <File name="Routing-${sd:id}" fileName="target/routing-purge-manual/routingtest-${sd:id}.log">
             <PatternLayout>
               <Pattern>%d %p %C{1.} [%t] %m%n</Pattern>
             </PatternLayout>
diff --git a/log4j-core/src/test/resources/log4j-routing.json b/log4j-core/src/test/resources/log4j-routing.json
index 809b3c2..4322d8d 100644
--- a/log4j-core/src/test/resources/log4j-routing.json
+++ b/log4j-core/src/test/resources/log4j-routing.json
@@ -15,9 +15,6 @@
  * limitations under the license.
  */
 { "configuration": { "status": "error", "name": "RoutingTest",
-      "properties": {
-        "property": { "name": "filename", "value" : "target/rolling1/rollingtest-$${sd:type}.log" }
-      },
     "ThresholdFilter": { "level": "debug" },
     "appenders": {
       "Console": { "name": "STDOUT",
@@ -31,7 +28,7 @@
           "Route": [
             {
               "RollingFile": {
-                "name": "Rolling-${sd:type}", "fileName": "${filename}",
+                "name": "Rolling-${sd:type}", "fileName": "target/rolling1/rollingtest-${sd:type}.log",
                 "filePattern": "target/rolling1/test1-${sd:type}.%i.log.gz",
                 "PatternLayout": {"pattern": "%d %p %C{1.} [%t] %m%n"},
                 "SizeBasedTriggeringPolicy": { "size": "500" }
diff --git a/log4j-core/src/test/resources/log4j-routing.properties b/log4j-core/src/test/resources/log4j-routing.properties
index c365e35..0dc7547 100644
--- a/log4j-core/src/test/resources/log4j-routing.properties
+++ b/log4j-core/src/test/resources/log4j-routing.properties
@@ -16,8 +16,6 @@
 status = error
 name = RoutingTest
 
-property.filename = target/routing1/routingtestProps-$${sd:type}.log
-
 filter.threshold.type = ThresholdFilter
 filter.threshold.level = debug
 
@@ -33,7 +31,7 @@ appender.routing.routes.pattern = $${sd:type}
 appender.routing.routes.route1.type = Route
 appender.routing.routes.route1.rolling.type = RollingFile
 appender.routing.routes.route1.rolling.name = Routing-${sd:type}
-appender.routing.routes.route1.rolling.fileName = ${filename}
+appender.routing.routes.route1.rolling.fileName = target/routing1/routingtestProps-${sd:type}.log
 appender.routing.routes.route1.rolling.filePattern = target/routing1/test1-${sd:type}.%i.log.gz
 appender.routing.routes.route1.rolling.layout.type = PatternLayout
 appender.routing.routes.route1.rolling.layout.pattern = %d %p %C{1.} [%t] %m%n
diff --git a/log4j-core/src/test/resources/log4j-routing.xml b/log4j-core/src/test/resources/log4j-routing.xml
index 4d83886..003f7d7 100644
--- a/log4j-core/src/test/resources/log4j-routing.xml
+++ b/log4j-core/src/test/resources/log4j-routing.xml
@@ -17,9 +17,6 @@
 
 -->
 <Configuration status="OFF" name="RoutingTest">
-  <Properties>
-    <Property name="filename">target/routing1/routingtest-$${sd:type}.log</Property>
-  </Properties>
   <ThresholdFilter level="debug"/>
 
   <Appenders>
@@ -32,7 +29,7 @@
     <Routing name="Routing">
       <Routes pattern="$${sd:type}">
         <Route>
-          <RollingFile name="Routing-${sd:type}" fileName="${filename}"
+          <RollingFile name="Routing-${sd:type}" fileName="target/routing1/routingtest-${sd:type}.log"
                        filePattern="target/routing1/test1-${sd:type}.%i.log.gz">
             <PatternLayout>
               <Pattern>%d %p %C{1.} [%t] %m%n</Pattern>
diff --git a/log4j-core/src/test/resources/log4j-routing2.json b/log4j-core/src/test/resources/log4j-routing2.json
index fe50b37..af67454 100644
--- a/log4j-core/src/test/resources/log4j-routing2.json
+++ b/log4j-core/src/test/resources/log4j-routing2.json
@@ -15,9 +15,6 @@
  * limitations under the license.
  */
 { "configuration": { "status": "error", "name": "RoutingTest",
-      "properties": {
-        "property": { "name": "filename", "value" : "target/rolling1/rollingtest-$${sd:type}.log" }
-      },
     "ThresholdFilter": { "level": "debug" },
     "appenders": {
       "appender": [
@@ -28,7 +25,7 @@
             "Route": [
               {
                 "RollingFile": {
-                  "name": "Rolling-${sd:type}", "fileName": "${filename}",
+                  "name": "Rolling-${sd:type}", "fileName": "target/rolling1/rollingtest-${sd:type}.log",
                   "filePattern": "target/rolling1/test1-${sd:type}.%i.log.gz",
                   "PatternLayout": {"pattern": "%d %p %C{1.} [%t] %m%n"},
                   "SizeBasedTriggeringPolicy": { "size": "500" }
diff --git a/log4j-core/src/test/resources/log4j2-pattern-layout-with-context.xml b/log4j-core/src/test/resources/log4j2-pattern-layout-with-context.xml
new file mode 100644
index 0000000..281e311
--- /dev/null
+++ b/log4j-core/src/test/resources/log4j2-pattern-layout-with-context.xml
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one or more
+ contributor license agreements.  See the NOTICE file distributed with
+ this work for additional information regarding copyright ownership.
+ The ASF licenses this file to You under the Apache License, Version 2.0
+ (the "License"); you may not use this file except in compliance with
+ the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+-->
+<Configuration status="DEBUG" packages="">
+	<Properties>
+		<Property name="pattern">%p %c $${ctx:user} $${event:Message}</Property>
+	</Properties>
+	<Appenders>
+		<List name="list">
+			<PatternLayout pattern="${pattern}"/>
+		</List>
+	</Appenders>
+
+	<Loggers>
+		<Root level="INFO">
+			<AppenderRef ref="list"/>
+		</Root>
+	</Loggers>
+</Configuration>
diff --git a/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/CustomLookup.java b/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/CustomLookup.java
index 8bd3415..2f9108e 100644
--- a/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/CustomLookup.java
+++ b/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/CustomLookup.java
@@ -50,6 +50,9 @@ public class CustomLookup extends AbstractLookup {
      */
     @Override
     public String lookup(final LogEvent event, final String key) {
+        if (event == null) {
+            return null;
+        }
         try {
             final Map<String, String> properties = loggerProperties.get(event.getLoggerName());
             if (properties == null) {
diff --git a/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/MapMessageLookup.java b/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/MapMessageLookup.java
index 5c444cb..59a01f0 100644
--- a/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/MapMessageLookup.java
+++ b/log4j-samples/log4j-samples-loggerProperties/src/main/java/org/apache/logging/log4j/lookup/MapMessageLookup.java
@@ -52,6 +52,9 @@ public class MapMessageLookup extends AbstractLookup {
      */
     @Override
     public String lookup(final LogEvent event, final String key) {
+        if (event == null) {
+            return null;
+        }
         final Message msg = event.getMessage();
         if (msg instanceof MapMessage) {
             try {
diff --git a/log4j-web/src/main/java/org/apache/logging/log4j/web/Log4jWebInitializerImpl.java b/log4j-web/src/main/java/org/apache/logging/log4j/web/Log4jWebInitializerImpl.java
index ce36076..37bcfc3 100644
--- a/log4j-web/src/main/java/org/apache/logging/log4j/web/Log4jWebInitializerImpl.java
+++ b/log4j-web/src/main/java/org/apache/logging/log4j/web/Log4jWebInitializerImpl.java
@@ -36,6 +36,7 @@ import org.apache.logging.log4j.core.async.AsyncLoggerContext;
 import org.apache.logging.log4j.core.config.Configurator;
 import org.apache.logging.log4j.core.impl.ContextAnchor;
 import org.apache.logging.log4j.core.impl.Log4jContextFactory;
+import org.apache.logging.log4j.core.lookup.ConfigurationStrSubstitutor;
 import org.apache.logging.log4j.core.lookup.Interpolator;
 import org.apache.logging.log4j.core.lookup.StrSubstitutor;
 import org.apache.logging.log4j.core.selector.ContextSelector;
@@ -62,7 +63,7 @@ final class Log4jWebInitializerImpl extends AbstractLifeCycle implements Log4jWe
     }
 
     private final Map<String, String> map = new ConcurrentHashMap<>();
-    private final StrSubstitutor substitutor = new StrSubstitutor(new Interpolator(map));
+    private final StrSubstitutor substitutor = new ConfigurationStrSubstitutor(new Interpolator(map));
     private final ServletContext servletContext;
 
     private String name;
diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index a5fa32b..c060fee 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -30,6 +30,9 @@
          - "remove" - Removed
     -->
     <release version="2.12.3" date="2021-12-dd" description="GA Release 2.12.3">
+      <action issue="LOG4J2-3230" dev="ckozak" type="fix">
+        Fix string substitution recursion.
+      </action>
       <action issue="LOG4J2-2819" dev="mattsicker" type="update">
         Add support for specifying an SSL configuration for SmtpAppender.
       </action>