{
  "from_raw": "Piotr Karwasz <pkarwasz@apache.org>",
  "from": "Piotr Karwasz <pk...@apache.org>",
  "gravatar": "048ae12808e1cc17af38403ee8600295",
  "to": "an...@apache.org,\n de...@logging.apache.org",
  "subject": "CVE-2026-34479: Apache Log4j 1 to Log4j 2 bridge: Silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters",
  "message-id": "<13145db8-dc7e-2018-efea-52db6989b49b@apache.org>",
  "mid": "gd0hp6mj17rn3kj279vgy4p7kd4zz5on",
  "permalinks": [
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    "r3eecebb62698f6f303b77592c5c96c4452fee6d4cdf48f7e2ae9874f@<announce.apache.org>"
  ],
  "dbid": "224dd194a879961073c2498ef0bf17d809971b3b3cff12d3d5cadb4357753274",
  "cc": "de...@logging.apache.org",
  "epoch": 1775828460,
  "list": "<announce.apache.org>",
  "list_raw": "<announce.apache.org>",
  "date": "2026/04/10 13:41:00",
  "private": false,
  "references": "",
  "in-reply-to": "",
  "body": "Severity: moderate \n\nAffected versions:\n\n- Apache Log4j 1 to Log4j 2 bridge (org.apache.logging.log4j:log4j-1.2-api) 2.7 before 2.25.4\n- Apache Log4j 1 to Log4j 2 bridge (org.apache.logging.log4j:log4j-1.2-api) 3.0.0-alpha1 through 3.0.0-beta2\n\nDescription:\n\nThe Log4j1XmlLayout from the Apache Log4j 1-to-Log4j 2 bridge fails to escape characters forbidden by the XML 1.0 standard, producing malformed XML output. Conforming XML parsers are required to reject documents containing such characters with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records.\n\nTwo groups of users are affected:\n\n  *  Those using Log4j1XmlLayout directly in a Log4j Core 2 configuration file.\n  *  Those using the Log4j 1 configuration compatibility layer with org.apache.log4j.xml.XMLLayout specified as the layout class.\n\n\nUsers are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version 2.25.4, which corrects this issue.\n\nNote: The Apache Log4j 1-to-Log4j 2 bridge is deprecated and will not be present in Log4j 3. Users are encouraged to consult the  Log4j 1 to Log4j 2 migration guide https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html , and specifically the section on eliminating reliance on the bridge.\n\nCredit:\n\nAp4sh (Samy Medjahed) and Ethicxz (Eliott Laurie) (original reporters) (finder)\njabaltarik1 (independently) (finder)\n\nReferences:\n\nhttps://github.com/apache/logging-log4j2/pull/4078\nhttps://logging.apache.org/security.html#CVE-2026-34479\nhttps://logging.apache.org/cyclonedx/vdr.xml\nhttps://logging.apache.org/log4j/2.x/migrate-from-log4j1.html\nhttps://logging.apache.org/\nhttps://www.cve.org/CVERecord?id=CVE-2026-34479\n\nTimeline:\n\n2026-02-16: Vulnerability reported by Ap4sh and ethicxz\n2026-03-15: Independent report received from jabaltarik1\n2026-03-24: Fix shared publicly by Piotr P. Karwasz as pull request #4078\n2026-03-25: Fix verified by reporter\n2026-03-28: Log4j 2.25.4 released\n\n",
  "body_short": "Severity: moderate \n\nAffected versions:\n\n- Apache Log4j 1 to Log4j 2 bridge (org.apache.logging.log4j:log4j-1.2-api) 2.7 before 2.25.4\n- Apache Log4j 1 to Log4j 2 bridge (org.apache.logging.log4j:log4j",
  "html_source_only": false,
  "attachments": [],
  "forum": "announce@apache.org",
  "size": 3997,
  "id": "gd0hp6mj17rn3kj279vgy4p7kd4zz5on"
}