# CVE-2026-34933: Avahi: Reachable assertion in `transport_flags_from_domain()` via conflicting publish flags crashes avahi-daemon

> An unprivileged local user can crash the Avahi daemon by sending a specific D-Bus call with conflicting flags, causing a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Apr 2026
- **Updated:** 11 Apr 2026
- **Also known as:** ALPINE-CVE-2026-34933, AZL-81959, BELL-CVE-2026-34933, DEBIAN-CVE-2026-34933, ECHO-a71e-9fdf-9b3d, GHSA-w65r-6gxh-vhvc, MINI-r3f8-676w-gv9w, OESA-2026-1854, OESA-2026-1982, OESA-2026-1983, OESA-2026-1984, OESA-2026-1985, OESA-2026-1986, ROOT-OS-DEBIAN-12-CVE-2026-34933, ROOT-OS-DEBIAN-13-CVE-2026-34933, SUSE-SU-2026:21417-1, SUSE-SU-2026:21631-1, SUSE-SU-2026:2296-1, SUSE-SU-2026:2297-1, UBUNTU-CVE-2026-34933, USN-8269-1, openSUSE-SU-2026:10670-1

## What is CVE-2026-34933?

CVE-2026-34933 is a medium-severity denial of service vulnerability in avahi, published on 3 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. Prior to version 0.9-rc4, any unprivileged local user can crash avahi-daemon by sending a single D-Bus method call with conflicting publish flags. This issue has been patched in version 0.9-rc4.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-34933?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `avahi` | openSUSE:Tumbleweed | All versions | 0.8-43.1 |

Products: Avahi Avahi.

## How do I fix CVE-2026-34933?

Upgrade to a fixed version.

## Is CVE-2026-34933 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34933 exists.

## 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-2026-24401](https://insights.sbomify.com/CVE-2026-24401/): Avahi has Uncontrolled Recursion in lookup_handle_cname function (medium 6.5)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34933 and fix it if it is affected.

What it is: CVE-2026-34933 is a medium-severity denial of service vulnerability in avahi, published on 3 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34933 exists.

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-2026-34933/ (Markdown: https://insights.sbomify.com/CVE-2026-34933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34933
- OSV: https://osv.dev/vulnerability/CVE-2026-34933

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34933/
Summaries are generated and may contain mistakes; the official description above is the record.