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Vulnerability · Published May 26, 2026 · Assigned by redhat

CVE-2026-42012Gnutls: gnutls: certificate validation bypass due to improper handling of uri and srv sans

High 7.1

In plain English

A high-severity improper certificate validation in gnutls. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.1High
Exploit odds (30 days)0.4%top 68.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10gnutls3.8.10-4.el10_2ALSA-2026:20613
AlmaLinux:8gnutls3.6.16-8.el8_10.6ALSA-2026:20611
AlmaLinux:9gnutls3.8.10-4.el9_8ALSA-2026:20612
AlmaLinux:10gnutls-c++3.8.10-4.el10_2ALSA-2026:20613
AlmaLinux:8gnutls-c++3.6.16-8.el8_10.6ALSA-2026:20611
AlmaLinux:9gnutls-c++3.8.10-4.el9_8ALSA-2026:20612
AlmaLinux:10gnutls-dane3.8.10-4.el10_2ALSA-2026:20613
AlmaLinux:8gnutls-dane3.6.16-8.el8_10.6ALSA-2026:20611
AlmaLinux:9gnutls-dane3.8.10-4.el9_8ALSA-2026:20612
AlmaLinux:10gnutls-devel3.8.10-4.el10_2ALSA-2026:20613
AlmaLinux:8gnutls-devel3.6.16-8.el8_10.6ALSA-2026:20611
AlmaLinux:9gnutls-devel3.8.10-4.el9_8ALSA-2026:20612
AlmaLinux:10gnutls-fips3.8.10-4.el10_2ALSA-2026:20613
AlmaLinux:10gnutls-utils3.8.10-4.el10_2ALSA-2026:20613
AlmaLinux:8gnutls-utils3.6.16-8.el8_10.6ALSA-2026:20611
AlmaLinux:9gnutls-utils3.8.10-4.el9_8ALSA-2026:20612
Alpine:v3.20gnutls3.8.13-r0ALPINE-CVE-2026-42012
Alpine:v3.21gnutls3.8.13-r0ALPINE-CVE-2026-42012
Alpine:v3.22gnutls3.8.13-r0ALPINE-CVE-2026-42012
Alpine:v3.23gnutls3.8.13-r0ALPINE-CVE-2026-42012
Alpine:v3.24gnutls3.8.13-r0ALPINE-CVE-2026-42012
Debian:12gnutls283.7.9-2+deb12u7DEBIAN-CVE-2026-42012
Debian:13gnutls283.8.9-3+deb13u4DEBIAN-CVE-2026-42012
Debian:14gnutls283.8.13-1DEBIAN-CVE-2026-42012
Rocky Linux:10gnutls0:3.8.10-4.el10_2RLSA-2026:20613
Rocky Linux:8gnutls0:3.6.16-8.el8_10.6RLSA-2026:20611
Rocky Linux:9gnutls0:3.8.10-4.el9_8RLSA-2026:20612
Ubuntu:22.04:LTSgnutls283.7.3-4ubuntu1.9UBUNTU-CVE-2026-42012
Ubuntu:24.04:LTSgnutls283.8.3-1.1ubuntu3.6UBUNTU-CVE-2026-42012
Ubuntu:25.10gnutls283.8.9-3ubuntu2.2UBUNTU-CVE-2026-42012
Ubuntu:26.04:LTSgnutls283.8.12-2ubuntu1.1UBUNTU-CVE-2026-42012

Affected products (as reported)

VendorProductVersions
gnutls 0
Red Hat Red Hat Enterprise Linux 10 see references
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support see references
Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION see references
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support see references
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On see references
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service see references
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service see references
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Enterprise Linux 9 see references
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions see references
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support see references
Red Hat Red Hat OpenShift Container Platform 4.20 see references
Red Hat Red Hat OpenShift Container Platform 4.21 see references
Red Hat Red Hat OpenShift Container Platform 4.22 see references
Red Hat Cert Manager support for Red Hat OpenShift release 1.17 see references
Red Hat Cert Manager support for Red Hat OpenShift release 1.17 see references
Red Hat Cert Manager support for Red Hat OpenShift release 1.17 see references

Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N

References