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CVE-2026-24401VulnerabilityPublished Updated

In versions 0.9rc2 and below, avahi-daemon can be crashed via a segmentation fault by sending an unsolicited mDNS

Affects avahiSource GCVE Database

0
Authoritative record:CVE-2026-24401· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium · fixed in 0.6.31-4ubuntu1.3+esm5 : update avahi when convenient.

Data as of 28 Oct 2026, 22:28 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.6.31-4ubuntu1.3+esm5, 0.6.32~rc+dfsg-1ubuntu2.3+esm5, 0.7-3.1ubuntu1.3+esm4 +4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 25.10avahipkg:deb/ubuntu/avahi?arch=source&distro=questingOther threatsAffected
  • <0.8-16ubuntu3.2
Fixed in
  • 0.8-16ubuntu3.2
Ubuntu 24.04 LTSavahipkg:deb/ubuntu/avahi?arch=source&distro=nobleOther threatsAffected
  • <0.8-13ubuntu6.2
Fixed in
  • 0.8-13ubuntu6.2
Ubuntu 22.04 LTSavahipkg:deb/ubuntu/avahi?arch=source&distro=jammyOther threatsAffected
  • <0.8-5ubuntu5.5
Fixed in
  • 0.8-5ubuntu5.5
Ubuntu Pro 20.04 LTSavahipkg:deb/ubuntu/avahi?arch=source&distro=esm-infra/focalOther threatsAffected
  • <0.7-4ubuntu7.3+esm2
Fixed in
  • 0.7-4ubuntu7.3+esm2
Ubuntu Pro 18.04 LTSavahipkg:deb/ubuntu/avahi?arch=source&distro=esm-infra/bionicOther threatsAffected
  • <0.7-3.1ubuntu1.3+esm4
  • =0.7-3ubuntu1
  • =0.7-3ubuntu2
Fixed in
  • 0.7-3.1ubuntu1.3+esm4
Ubuntu Pro 16.04 LTSavahipkg:deb/ubuntu/avahi?arch=source&distro=esm-infra/xenialOther threatsAffected
  • <0.6.32~rc+dfsg-1ubuntu2.3+esm5
Fixed in
  • 0.6.32~rc+dfsg-1ubuntu2.3+esm5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

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, which is part of version 0.9-rc3.

References

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