CVE-2025-66168

Name	CVE-2025-66168
Description	Apache ActiveMQ does not properly validate the remaining length field which may lead to an overflow during the decoding of malformed packets. When this integer overflow occurs, ActiveMQ may incorrectly compute the total Remaining Length and subsequently misinterpret the payload as multiple MQTT control packets which makes the broker susceptible to unexpected behavior when interacting with non-compliant clients. This behavior violates the MQTT v3.1.1 specification, which restricts Remaining Length to a maximum of 4 bytes. The scenario occurs on established connections after the authentication process. Brokers that are not enabling mqtt transport connectors are not impacted. This issue affects Apache ActiveMQ: before 5.19.2, 6.0.0 to 6.1.8, and 6.2.0 Users are recommended to upgrade to version 5.19.2, 6.1.9, or 6.2.1, which fixes the 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
activemq (PTS)	bullseye	5.16.1-1	vulnerable
	bullseye (security)	5.16.1-1+deb11u2	vulnerable
	bookworm, bookworm (security)	5.17.2+dfsg-2+deb12u1	vulnerable
	sid, trixie	5.17.6+dfsg-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
activemq	source	(unstable)	(unfixed)

Notes

https://www.openwall.com/lists/oss-security/2026/03/03/5
https://issues.apache.org/jira/browse/AMQ-9810
Fixed by: https://github.com/apache/activemq/commit/3f0720c085b24f25c98e414fefc007bc42470ee3 (activemq-5.19.2)
Fixed by: https://github.com/apache/activemq/commit/ebed70bcd221e91d303576bdbd8acd357b914259 (activemq-5.19.2)