Avahi CVE-2026-24401

MEDIUM

Uncontrolled Recursion (CWE-674)

2026-01-24 security-advisories@github.com

Denial Of Service Canonical Avahi

6.5

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-674 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Recursion depth limits
Impact	CVSS 6.5 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: Required. Exploitable via remote/network.
Exploit ScenarioDerived	A remote attacker could exploit this flaw, stack exhaustion.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Avahi daemon versions 0.9rc2 and below can be remotely crashed through a denial of service attack by sending a specially crafted mDNS response with a recursive CNAME record pointing to itself, triggering unbounded recursion and stack exhaustion. This vulnerability affects systems using multicast record browsers, including those relying on nss-mdns for service discovery. A patch is available for affected installations.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:59 CVSS 6.5

Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. [CVSS 6.5 MEDIUM]

RemediationAI

A vendor patch is available — apply it immediately. Restrict network access to the affected service where possible.

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Technical ContextAI · show details

Classified as CWE-674 (Uncontrolled Recursion). Affects the lookup_handle_cname component of 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 rec

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.5 MEDIUM

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

SUSE MEDIUM

Red Hat 6.5 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

2

Patch released

Feb 12, 2026 - 15:58 nvd

Patch available

CVE Published

Jan 24, 2026 - 02:15 nvd

MEDIUM 6.5

DescriptionNVD

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.

Executive ViewAI

Why It Matters

Organizations using Avahi should be aware of notable risk from CVE-2026-24401 rated CVSS 6.5. Exploitation could compromise the security of affected deployments. A patch is available and should be applied during regular vulnerability management.

Business Impact: Moderate

Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score

0.0%

Top 89% exploitable

Data Quality

5 sources

Confidence: Medium

CVE.org

EPSS Vendor

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

No

Priority Score

32

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +32

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)NVD

cpe:2.3:a:avahi:avahi:*:*:*:*:*:*:*:*

cpe:2.3:a:avahi:avahi:0.9:rc1:*:*:*:*:*:*

cpe:2.3:a:avahi:avahi:0.9:rc2:*:*:*:*:*:*

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Same weakness CWE-674 – Uncontrolled Recursion

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Vendor StatusVendor

SUSE

Severity: Medium

Product	Status
Container suse/sle-micro-rancher/5.2:latest	Affected
SUSE Linux Enterprise Micro 5.2	Fixed
SUSE Linux Enterprise Micro 5.3	Affected
SUSE Linux Enterprise Micro 5.4	Affected
SUSE Linux Enterprise Micro 5.5	Affected

References

Advisories & patches

PATCH https://github.com/avahi/avahi/commit/78eab31128479f06e30beb8c1cbf99dd921e2524 PATCH https://github.com/avahi/avahi/issues/501 ADVISORY https://github.com/avahi/avahi/security/advisories/GHSA-h4vp-5m8j-f6w3 ADVISORY https://ubuntu.com/security/notices/USN-8269-1 ADVISORY https://vuldb.com/vuln/342788 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:1191/

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