cvedb.io
CVE-2026-34479
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2026-04-10T16:16:31.270 · Last modified 2026-06-17T10:39:06.947

Summary

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

Affected products

apache — log4j

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.