Avahi has Uncontrolled Recursion in lookup_handle_cname function

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-24401
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-24 02:15:48 UTC
Updated2026-10-23 16:16:51 UTC
DescriptionAvahi 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Problem Types: CWE-674 | CWE-674 CWE-674: Uncontrolled Recursion

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Avahi Avahi All All All All
Application Avahi Avahi 0.9 rc1 All All
Application Avahi Avahi 0.9 rc2 All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Avahi Avahi affected < 0.9-rc3 Not specified

References

ReferenceSourceLinkTags
github.com/avahi/avahi/security/advisories/GHSA-h4vp-5m8j-f6w3 [email protected] github.com Vendor Advisory
github.com/avahi/avahi/commit/78eab31128479f06e30beb8c1cbf99dd921e2524 [email protected] github.com Patch
github.com/avahi/avahi/issues/501 [email protected] github.com Issue Tracking, Patch
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