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CVE-2026-42012

32
FAUCET Score

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.

First published: May 26, 2026Last modified: Jul 22, 2026

Impacted Technologies

VendorProductVersion(s)CPE
Red HatRed Hat Enterprise Linux 8
Range not provided by sourceCNA affecteddefault affected
Red HatRed Hat Enterprise Linux 9
Range not provided by sourceCNA affecteddefault affected
Red HatRed Hat OpenShift Container Platform 4
All Versions ImpactedCNA affecteddefault affected
Red HatRed Hat OpenShift Container Platform 4
Range not provided by sourceCNA affecteddefault unknown
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Range not provided by sourceCNA affecteddefault affected

CVSS Data

CVSS version used by this source: 3.1

7.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
4.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.35%
Probability of exploitation in next 30 days
EPSS Percentile
28.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0035 is in the 32nd percentile among its peer group of 14,875 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.1 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

microsoftpatch availablevia msrc
Product: 21391-17084Fixed in: 3.8.13-1
microsoftpatch availablevia msrc
Product: azl3 gnutls 3.8.3-11 on Azure Linux 3.0Fixed in: 3.8.13-1
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (questing)Fixed in: 3.8.9-3ubuntu2.2
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (resolute)Fixed in: 3.8.12-2ubuntu1.1
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (bionic)Fixed in: 3.5.18-1ubuntu1.6+esm4
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (focal)Fixed in: 3.6.13-2ubuntu1.12+esm3
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (jammy)Fixed in: 3.7.3-4ubuntu1.9
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (xenial)Fixed in: 3.4.10-4ubuntu1.9+esm4
ubuntupatch availablevia ubuntu_usn
Product: gnutls28 (noble)Fixed in: 3.8.3-1.1ubuntu3.6

Vendor Advisories (3)

ubuntuUSN-8539-1

GnuTLS vulnerabilities

Jul 14, 2026
ubuntuUSN-8284-1

GnuTLS vulnerabilities

May 20, 2026
microsoft2026-May/CVE-2026-42012Important

Gnutls: gnutls: certificate validation bypass due to improper handling of uri and srv sans

May 12, 2026

References

access.redhat.com / errata/RHSA-2026:13274
access.redhat.com / errata/RHSA-2026:20611
access.redhat.com / errata/RHSA-2026:20612
access.redhat.com / errata/RHSA-2026:20613
access.redhat.com / errata/RHSA-2026:26319
access.redhat.com / errata/RHSA-2026:26409
access.redhat.com / errata/RHSA-2026:29197
access.redhat.com / errata/RHSA-2026:30004
access.redhat.com / errata/RHSA-2026:30849
access.redhat.com / errata/RHSA-2026:30850
access.redhat.com / errata/RHSA-2026:32962
access.redhat.com / errata/RHSA-2026:33125
access.redhat.com / errata/RHSA-2026:41921
access.redhat.com / errata/RHSA-2026:43575
access.redhat.com / security/cve/CVE-2026-42012
bugzilla.redhat.com / show_bug.cgi
gnutls.org / security-new.html