[ANNOUNCE] Apache Log4j 2.16.0 Released

[Matt Sicker <ma...@apache.org>]

The Apache Log4j 2 team is pleased to announce the Log4j 2.16.0 release!

Apache Log4j is a well known framework for logging application
behavior. Log4j 2 is an upgrade to Log4j that provides significant
improvements over its predecessor, Log4j 1.x, and provides many other
modern features such as support for Markers, lambda expressions for
lazy logging, property substitution using Lookups, multiple patterns
on a PatternLayout and asynchronous Loggers. Another notable Log4j 2
feature is the ability to be "garbage-free" (avoid allocating
temporary objects) while logging. In addition, Log4j 2 will not lose
events while reconfiguring.

The artifacts may be downloaded from
https://logging.apache.org/log4j/2.x/download.html.

This release contains one change which is noted below.

Due to a break in compatibility in the SLF4J binding, Log4j now ships
with two versions of the SLF4J to Log4j adapters. log4j-slf4j-impl
should be used with SLF4J 1.7.x and earlier and log4j-slf4j18-impl
should be used with SLF4J 1.8.x and later. SLF4J-2.0.0 alpha releases
are not fully supported. See
https://issues.apache.org/jira/browse/LOG4J2-2975 and
https://jira.qos.ch/browse/SLF4J-511.

Some of the changes in Log4j 2.16.0 include:

* Removed Message Lookups. This is a hardening related to changes made
to prevent CVE-2021-44228. While this change is recommended, it is NOT
required to fix CVE-2021-44228.
* While release 2.15.0 removed the ability to resolve Lookups and log
messages and addressed issues with how JNDI is accessed, the Log4j
team feels that having JNDI enabled by default introduces an undue
risk for our users. Starting in version 2.16.0, JNDI functionality is
disabled by default and can be re-enabled via the log4j2.enableJndi
system property. Use of JNDI in an unprotected context is a large
security risk and should be treated as such in both this library and
all other Java libraries using JNDI.
* Prior to version 2.15.0, Log4j would automatically resolve Lookups
contained in the message or its parameters in the Pattern Layout. This
behavior is no longer the default and must be enabled by specifying
%msg{lookup}.

The Log4j 2.16.0 API, as well as many core components, maintains
binary compatibility with previous releases. This version is
recommended as an upgrade

GA Release 2.16.0

Changes in this version include:

Fixed Bugs

LOG4J2-3208: Disable JNDI by default. Require log4j2.enableJndi to be
set to true to allow JNDI.
LOG4J2-3211: Completely remove support for Message Lookups.

________________________________

Apache Log4j 2.16.0 requires a minimum of Java 8 to build and run.
Log4j 2.12.1 is the last release to support Java 7. Java 7 is no
longer supported by the Log4j team.

For complete information on Apache Log4j 2, including instructions on
how to submit bug reports, patches, or suggestions for improvement,
see the Apache Apache Log4j 2 website:

https://logging.apache.org/log4j/2.x/

-- 
Matt Sicker
PMC Member, Logging Services, Apache Software Foundation