CVE-2026-34481

Name	CVE-2026-34481
Description	Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, or -Infinity), which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to index affected records. An attacker can exploit this issue only if both of the following conditions are met: * The application uses JsonTemplateLayout. * The application logs a MapMessage containing an attacker-controlled floating-point value. Users are advised to upgrade to Apache Log4j JSON Template Layout 2.25.4, which corrects this issue.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
apache-log4j1.2 (PTS)	bullseye	1.2.17-10+deb11u1	fixed
	bookworm, forky, sid, trixie	1.2.17-11	fixed
apache-log4j2 (PTS)	bullseye	2.17.1-1~deb11u1	vulnerable
	bullseye (security)	2.17.1-1~deb11u2	vulnerable
	bookworm, forky, sid, trixie	2.19.0-2	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
apache-log4j1.2	source	(unstable)	(not affected)
apache-log4j2	source	(unstable)	(unfixed)

Notes

- apache-log4j1.2 <not-affected> (Vulnerable code not present)
https://lists.apache.org/thread/n34zdv00gbkdbzt2rx9rf5mqz6lhopcv
https://logging.apache.org/security.html#CVE-2026-34481
https://github.com/apache/logging-log4j2/pull/4080
Fixed by: https://github.com/apache/logging-log4j2/commit/2c4dd1db372c59ad73aca88e281635fe30072268 (rel/2.25.4)