A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4595-1 gnutls28 security update
Debian DSA Debian DSA DSA-6281-1 gnutls28 security update
Ubuntu USN Ubuntu USN USN-8284-1 GnuTLS vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 28 May 2026 22:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 27 May 2026 10:30:00 +0000

Type Values Removed Values Added
First Time appeared Gnu
Gnu gnutls
Redhat hardened Images
Redhat openshift Container Platform
Vendors & Products Gnu
Gnu gnutls
Redhat hardened Images
Redhat openshift Container Platform

Wed, 27 May 2026 03:30:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:8 cpe:/a:redhat:enterprise_linux:8::appstream
cpe:/o:redhat:enterprise_linux:8::baseos
References

Tue, 26 May 2026 21:45:00 +0000

Type Values Removed Values Added
Description A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.
Title Gnutls: gnutls: certificate validation bypass due to oversized subject alternative name
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat openshift
Weaknesses CWE-1284
CPEs cpe:/a:redhat:hummingbird:1
cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat openshift
References
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-05-28T14:13:58.434Z

Reserved: 2026-04-23T11:23:46.517Z

Link: CVE-2026-42013

cve-icon Vulnrichment

Updated: 2026-05-28T14:13:54.446Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-05-26T22:16:42.050

Modified: 2026-05-27T14:54:20.160

Link: CVE-2026-42013

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-27T10:08:14Z

Weaknesses