CVE-2026-42012

Publication date 30 April 2026

Last updated 16 July 2026

Ubuntu priority

Cvss 3 Severity Score

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
	18.04 LTS bionic	Fixed 3.5.18-1ubuntu1.6+esm4
	16.04 LTS xenial	Fixed 3.4.10-4ubuntu1.9+esm4

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
gnutls28	Upstream: 8dcc6a1

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

Related Ubuntu Security Notices (USN)

USN-8284-1
GnuTLS vulnerabilities
20 May 2026

USN-8539-1
GnuTLS vulnerabilities
14 July 2026