# CVE-2026-0967: Libssh: libssh: denial of service via inefficient regular expression processing

> A remote attacker can cause a denial of service in libssh clients by crafting specific hostnames that trigger inefficient regular expression backtracking.

- **Severity:** Low 2.2 (`CVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 26 Mar 2026
- **Updated:** 1 Sep 2026
- **Also known as:** AZL-81092, BELL-CVE-2026-0967, DEBIAN-CVE-2026-0967, ECHO-ce8c-f3b6-b79f, GHSA-6jpg-fr24-wpvf, JLSEC-2026-782, MINI-7x3j-23cc-72pp, UBUNTU-CVE-2026-0967

## What is CVE-2026-0967?

CVE-2026-0967 is a low-severity denial of service vulnerability in Redhat Enterprise Linux, published on 26 Mar 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

A flaw was found in libssh. A remote attacker, by controlling client configuration files or known_hosts files, could craft specific hostnames that when processed by the `match_pattern()` function can lead to inefficient regular expression backtracking. This can cause timeouts and resource exhaustion, resulting in a Denial of Service (DoS) for the client.

Weakness: CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-0967?

It affects 2 products.


Products: Libssh Libssh, Redhat Enterprise Linux.

## How do I fix CVE-2026-0967?

Apply the vendor's patch.

## Is CVE-2026-0967 being exploited?

There is no known exploitation of CVE-2026-0967 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2026-59851](https://insights.sbomify.com/CVE-2026-59851/): Libssh: libssh: authentication bypass via missing gssapi principal check (high 8.8)
- [CVE-2025-5987](https://insights.sbomify.com/CVE-2025-5987/): Libssh: invalid return code for chacha20 poly1305 with openssl backend (high 8.1)
- [CVE-2025-14821](https://insights.sbomify.com/CVE-2025-14821/): Libssh: libssh: insecure default configuration leads to local man-in-the-middle attacks on windows (high 7.8)
- [CVE-2012-4560](https://insights.sbomify.com/CVE-2012-4560/): Memory corruption in n/a (high 7.5)
- [CVE-2012-4562](https://insights.sbomify.com/CVE-2012-4562/): Integer overflow in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-0967 and fix it if it is affected.

What it is: CVE-2026-0967 is a low-severity denial of service vulnerability in Redhat Enterprise Linux, published on 26 Mar 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-0967 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-2026-0967/ (Markdown: https://insights.sbomify.com/CVE-2026-0967/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-0967
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-0967
- OSV: https://osv.dev/vulnerability/CVE-2026-0967

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-0967/
Summaries are generated and may contain mistakes; the official description above is the record.