CVE-2026-24401

Name	CVE-2026-24401
Description	Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In versions 0.9rc2 and below, avahi-daemon can be crashed via a segmentation fault by sending an unsolicited mDNS response containing a recursive CNAME record, where the alias and canonical name point to the same domain (e.g., "h.local" as a CNAME for "h.local"). This causes unbounded recursion in the lookup_handle_cname function, leading to stack exhaustion. The vulnerability affects record browsers where AVAHI_LOOKUP_USE_MULTICAST is set explicitly, which includes record browsers created by resolvers used by nss-mdns. This issue is patched in commit 78eab31128479f06e30beb8c1cbf99dd921e2524.
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)
Debian Bugs	1126342

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
avahi (PTS)	bullseye	0.8-5+deb11u2	vulnerable
	bullseye (security)	0.8-5+deb11u3	vulnerable
	bookworm	0.8-10+deb12u1	vulnerable
	trixie	0.8-16	vulnerable
	forky, sid	0.8-17	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
avahi	source	(unstable)	(unfixed)			1126342

Notes

https://github.com/avahi/avahi/security/advisories/GHSA-h4vp-5m8j-f6w3
https://github.com/avahi/avahi/issues/501
Fixed by: https://github.com/avahi/avahi/commit/78eab31128479f06e30beb8c1cbf99dd921e2524