# CVE-2026-35091: Corosync: corosync: denial of service and information disclosure via crafted udp packet

> Remote attackers can cause denial of service and disclose memory contents in Corosync by sending crafted UDP packets, affecting Linux distributions.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Apr 2026
- **Updated:** 21 Aug 2026
- **Also known as:** AZL-81981, DEBIAN-CVE-2026-35091, GHSA-hmg2-5h4j-37m9, UBUNTU-CVE-2026-35091, openSUSE-SU-2026:10488-1

## What is CVE-2026-35091?

CVE-2026-35091 is a high-severity denial of service vulnerability in Redhat Enterprise Linux, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in Corosync. A remote unauthenticated attacker can exploit a wrong return value vulnerability in the Corosync membership commit token sanity check by sending a specially crafted User Datagram Protocol (UDP) packet. This can lead to an out-of-bounds read, causing a denial of service (DoS) and potentially disclosing limited memory contents

Weakness: CWE-253 (Incorrect Check of Function Return Value)

## Which versions are affected by CVE-2026-35091?

It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `corosync` | openSUSE:Tumbleweed | All versions | 3.1.10-4.1 |

Products: Corosync Corosync, Redhat Enterprise Linux, Redhat Openshift.

## How do I fix CVE-2026-35091?

Apply the vendor's patch.

## Is CVE-2026-35091 being exploited?

There is no known exploitation of CVE-2026-35091 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2025-30472](https://insights.sbomify.com/CVE-2025-30472/): Memory corruption in Corosync (critical 9.0)
- [CVE-2026-35092](https://insights.sbomify.com/CVE-2026-35092/): Corosync: corosync: denial of service via integer overflow in join message validation (high 7.5)
- [CVE-2013-0250](https://insights.sbomify.com/CVE-2013-0250/): Denial of service in n/a (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-35091 and fix it if it is affected.

What it is: CVE-2026-35091 is a high-severity denial of service vulnerability in Redhat Enterprise Linux, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-35091 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. 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-2026-35091/ (Markdown: https://insights.sbomify.com/CVE-2026-35091/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35091
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35091
- OSV: https://osv.dev/vulnerability/CVE-2026-35091

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-35091/
Summaries are generated and may contain mistakes; the official description above is the record.