CVE-2026-40356

Name	CVE-2026-40356
Description	In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, possibly causing the process to terminate in parse_message.
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
krb5 (PTS)	bullseye	1.18.3-6+deb11u5	vulnerable
	bullseye (security)	1.18.3-6+deb11u7	vulnerable
	bookworm	1.20.1-2+deb12u4	vulnerable
	bookworm (security)	1.20.1-2+deb12u2	vulnerable
	trixie	1.21.3-5	vulnerable
	forky, sid	1.22.1-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
krb5	source	(unstable)	(unfixed)

https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f