---
title: "CVE-2026-42012\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2026-42012?format=md
keywords: index, follow
---

# CVE-2026-42012

Publication date 30 April 2026

Last updated 16 July 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**7.1 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2026-42012?format=md#impact-score)

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## Description

A flaw was found in gnutls. A remote attacker could exploit this
vulnerability by presenting a specially crafted certificate that contains
Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative
Names (SANs). This could cause the certificate validation process to
incorrectly fall back to checking DNS hostnames against the Common Name
(CN), potentially allowing the attacker to spoof legitimate services or
intercept sensitive information.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| gnutls28 | 26.04 LTS resolute | Fixed 3.8.12-2ubuntu1.1 |
| 25.10 questing | Fixed 3.8.9-3ubuntu2.2 |
| 24.04 LTS noble | Fixed 3.8.3-1.1ubuntu3.6 |
| 22.04 LTS jammy | Fixed 3.7.3-4ubuntu1.9 |
| 20.04 LTS focal | Fixed 3.6.13-2ubuntu1.12+esm3  Ubuntu Pro |
| 18.04 LTS bionic | Fixed 3.5.18-1ubuntu1.6+esm4  Ubuntu Pro |
| 16.04 LTS xenial | Fixed 3.4.10-4ubuntu1.9+esm4  Ubuntu Pro |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2026-42012?format=md#patch-details)

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### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| gnutls28 | * Upstream:   [8dcc6a1](https://gitlab.com/gnutls/gnutls/-/commit/8dcc6a1f48945997666ac9f10896819edd01a03b) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.1 · High

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | Required |
  | Scope | Unchanged |
  | Confidentiality impact | Low |
  | Integrity impact | High |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.1 · High |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-42012)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-42012)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-42012)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-42012)

### Related Ubuntu Security Notices (USN)

+ [USN-8284-1](https://usn.ubuntu.com/USN-8284-1)
+ GnuTLS vulnerabilities
+ 20 May 2026

+ [USN-8539-1](https://usn.ubuntu.com/USN-8539-1)
+ GnuTLS vulnerabilities
+ 14 July 2026

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-42012>
* <https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-7>