๐Ÿ›ก๏ธ CVE-2026-34479
๐ŸŸ  CVSS 7.5 โ€” High โš ๏ธ Exploit Public CWE-116 NVD
7.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

Details

Severity HIGH
CVSS Score 7.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE CWE-116
Public Exploit โš ๏ธ Yes
Source NVD
Published 2026-04-10
Updated 2026-06-15
Modified 2026-05-06

Affected Packages

Software From version Fixed in
log4j โ€” โ€”
org.apache.logging.log4j:log4j-1.2-api 3.0.0-beta1 โ€”

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