GHSA-h383-gmxw-35v2

Dashboard / Vulnerabilities / GHSA-h383-gmxw-35v2

GHSA-h383-gmxw-35v2

Summary: Apache Log4j 1 to Log4j 2 bridge: silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters

Details: The `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. Two groups of users are affected: * Those using `Log4j1XmlLayout` directly in a Log4j Core 2 configuration file. * Those using the Log4j 1 configuration compatibility layer with `org.apache.log4j.xml.XMLLayout` specified as the layout class. Users are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version `2.25.4`, which corrects this issue. > [!NOTE] > 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.

References: https://nvd.nist.gov/vuln/detail/CVE-2026-34479, https://github.com/apache/logging-log4j2/pull/4078, https://github.com/apache/logging-log4j2, https://lists.apache.org/thread/gd0hp6mj17rn3kj279vgy4p7kd4zz5on, https://logging.apache.org/cyclonedx/vdr.xml, https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html, https://logging.apache.org/security.html#CVE-2026-34479, http://www.openwall.com/lists/oss-security/2026/04/10/8