CVE-2026-35091

Name	CVE-2026-35091
Description	A flaw was found in Corosync. A remote unauthenticated attacker can exploit a wrong return value vulnerability in the Corosync membership commit token sanity check by sending a specially crafted User Datagram Protocol (UDP) packet. This can lead to an out-of-bounds read, causing a denial of service (DoS) and potentially disclosing limited memory contents. This vulnerability affects Corosync when running in totemudp/totemudpu mode, which is the default configuration.
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)
References	DSA-6261-1
Debian Bugs	1133838

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
corosync (PTS)	bullseye	3.1.2-2	vulnerable
	bullseye (security)	3.1.2-2+deb11u1	vulnerable
	bookworm	3.1.7-1+deb12u1	vulnerable
	bookworm (security)	3.1.7-1+deb12u2	fixed
	trixie	3.1.9-2	vulnerable
	trixie (security)	3.1.9-2+deb13u1	fixed
	forky	3.1.10-1	vulnerable
	sid	3.1.10-2	fixed

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

Package	Type	Release	Fixed Version	Origin	Debian Bugs
corosync	source	bookworm	3.1.7-1+deb12u2	DSA-6261-1
corosync	source	trixie	3.1.9-2+deb13u1	DSA-6261-1
corosync	source	(unstable)	3.1.10-2		1133838

Notes

https://bugzilla.redhat.com/show_bug.cgi?id=2453813
https://bugzilla.redhat.com/show_bug.cgi?id=2453169
https://github.com/corosync/corosync/commit/a16614accfdb3481264d7281843fadf439d9ab1b