# CVE-2026-24401: Avahi has Uncontrolled Recursion in lookup_handle_cname function

> An attacker can crash the Avahi daemon by sending a malicious mDNS response with a recursive CNAME, causing stack exhaustion in specific configurations.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Jan 2026
- **Updated:** 23 Oct 2026
- **Also known as:** ALPINE-CVE-2026-24401, AZL-75204, AZL-75207, BELL-CVE-2026-24401, CLSA-2026-1773137055, CLSA-2026-1778112033, DEBIAN-CVE-2026-24401, ECHO-e408-9130-b921, GHSA-h4vp-5m8j-f6w3, MINI-9569-j92w-g8hr, OESA-2026-1450, ROOT-OS-DEBIAN-12-CVE-2026-24401, ROOT-OS-DEBIAN-13-CVE-2026-24401, SUSE-SU-2026:1191-1, SUSE-SU-2026:1441-1, SUSE-SU-2026:1442-1, SUSE-SU-2026:21117-1, SUSE-SU-2026:21127-1, openSUSE-SU-2026:10701-1

## What is CVE-2026-24401?

CVE-2026-24401 is a medium-severity denial of service vulnerability in avahi, published on 24 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-24401?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `avahi` | SUSE:Linux Enterprise Micro 5.2 | All versions | 0.7-150100.3.49.1 |
| `avahi` | SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 0.8-150600.15.15.1 |
| `avahi-glib2` | SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 0.8-150600.15.15.1 |
| `avahi` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP7 | All versions | 0.8-150600.15.15.1 |
| `avahi-glib2` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP7 | All versions | 0.8-150600.15.15.1 |
| `avahi` | SUSE:Linux Enterprise Module for Package Hub 15 SP7 | All versions | 0.8-150600.15.15.1 |
| `avahi` | SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 0.6.32-32.39.1 |
| `avahi` | SUSE:Linux Micro 6.0 | All versions | 0.8-8.1 |
| `avahi` | SUSE:Linux Micro 6.1 | All versions | 0.8-slfo.1.1_5.1 |
| `avahi` | openSUSE:Leap 15.6 | All versions | 0.8-150600.15.15.1 |
| `avahi-glib2` | openSUSE:Leap 15.6 | All versions | 0.8-150600.15.15.1 |
| `avahi-qt5` | openSUSE:Leap 15.6 | All versions | 0.8-150600.15.15.1 |
| `avahi` | openSUSE:Tumbleweed | All versions | 0.8-44.1 |

Products: Avahi Avahi.

## How do I fix CVE-2026-24401?

Apply the vendor's patch.

## Is CVE-2026-24401 being exploited?

There is no known exploitation of CVE-2026-24401 in the wild and no public exploit code.

## Other vulnerabilities in avahi

- [CVE-2017-6519](https://insights.sbomify.com/CVE-2017-6519/): Denial of service in n/a (critical 9.1)
- [CVE-2021-26720](https://insights.sbomify.com/CVE-2021-26720/): Path traversal in n/a (high 7.8)
- [CVE-2025-68468](https://insights.sbomify.com/CVE-2025-68468/): Avahi has a reachable assertion in lookup_multicast_callback (medium 6.5)
- [CVE-2025-68471](https://insights.sbomify.com/CVE-2025-68471/): Avahi has a reachable assertion in lookup_start (medium 6.5)
- [CVE-2023-38469](https://insights.sbomify.com/CVE-2023-38469/): Reachable assertion in avahi_dns_packet_append_record (medium 6.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-24401 and fix it if it is affected.

What it is: CVE-2026-24401 is a medium-severity denial of service vulnerability in avahi, published on 24 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-24401 in the wild and no public exploit code.

Affected product: avahi. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-24401/ (Markdown: https://insights.sbomify.com/CVE-2026-24401/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-24401
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-24401
- OSV: https://osv.dev/vulnerability/CVE-2026-24401

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-24401/
Summaries are generated and may contain mistakes; the official description above is the record.