CVE-2026-24401 — Avahi has Uncontrolled Recursion in lookup_handle_cname function

Affected: avahi

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.

USN-8269-1 — avahi vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: avahi, Ubuntu:Pro:16.04:LTS: avahi, Ubuntu:Pro:18.04:LTS: avahi, Ubuntu:Pro:20.04:LTS: avahi, Ubuntu:22.04:LTS: avahi, Ubuntu:24.04:LTS: avahi, Ubuntu:25.10: avahi, Ubuntu:26.04:LTS: avahi

It is discovered that Avahi incorrectly handled crafted input. A remote attacker could possibly use this issue to crash the program, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS and Ubuntu 24.04 LTS. (CVE-2026-24401)

Guillaume Meunier discovered that Avahi incorrectly handled crafted input. An attacker could possibly use this issue to crash the program, resulting in a denial of service. (CVE-2026-34933)

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CVE-2026-24401 — Avahi has Uncontrolled Recursion in lookup_handle_cname function

USN-8269-1 — avahi vulnerabilities