---
id: CVE-2026-24401
title: Avahi has Uncontrolled Recursion in lookup_handle_cname function
summary: >-
  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
  conta…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-674
vendor: avahi
product: avahi
affected:
  - avahi < 0.9-rc3
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-01-26T16:14:24.982686Z'
published: '2026-01-24'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T15:54:16.116Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-24401'
references:
  - url: 'https://github.com/avahi/avahi/security/advisories/GHSA-h4vp-5m8j-f6w3'
    label: 'https://github.com/avahi/avahi/security/advisories/GHSA-h4vp-5m8j-f6w3'
  - url: 'https://github.com/avahi/avahi/issues/501'
    label: 'https://github.com/avahi/avahi/issues/501'
  - url: >-
      https://github.com/avahi/avahi/commit/78eab31128479f06e30beb8c1cbf99dd921e2524
    label: >-
      https://github.com/avahi/avahi/commit/78eab31128479f06e30beb8c1cbf99dd921e2524
tags:
  - cve.org
epss: 0.00303
epssPercentile: 0.2192
ingestedAt: '2026-10-23T16:31:11.325Z'
---

## Overview

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, which is part of version 0.9-rc3.

## Affected

- `avahi < 0.9-rc3`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.