# CVE-2026-42011: Gnutls: gnutls: security bypass due to incorrect name constraint handling

> Remote attackers can bypass certificate name constraints in GnuTLS, enabling spoofing or man-in-the-middle attacks against systems using affected versions.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 May 2026
- **Updated:** 29 Oct 2026
- **Also known as:** ALPINE-CVE-2026-42011, BELL-CVE-2026-42011, CLSA-2026-1791496727, CLSA-2026-1791497467, CLSA-2026-1791497901, DEBIAN-CVE-2026-42011, ECHO-00bb-2656-b63a, GHSA-568w-37qx-3qc6

## What is CVE-2026-42011?

CVE-2026-42011 is a high-severity vulnerability in Cert Manager support for Red Hat OpenShift release 1.17, published on 7 May 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 gnutls. This vulnerability occurs because permitted name constraints were incorrectly ignored when previous Certificate Authorities (CAs) only had excluded name constraints. A remote attacker could exploit this to bypass critical name constraint checks during certificate validation. This bypass could lead to the acceptance of invalid certificates, potentially enabling spoofing or man-in-the-middle attacks against affected systems.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-42011?


## How do I fix CVE-2026-42011?

Apply the vendor's patch.

## Is CVE-2026-42011 being exploited?

There is no known exploitation of CVE-2026-42011 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42011 and fix it if it is affected.

What it is: CVE-2026-42011 is a high-severity vulnerability in Cert Manager support for Red Hat OpenShift release 1.17, published on 7 May 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-2026-42011 in the wild and no public exploit code.

Affected product: Cert Manager support for Red Hat OpenShift release 1.17. 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-2026-42011/ (Markdown: https://insights.sbomify.com/CVE-2026-42011/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42011
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42011
- OSV: https://osv.dev/vulnerability/CVE-2026-42011

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42011/
Summaries are generated and may contain mistakes; the official description above is the record.