CVE-2026-42013

high

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.

References

https://access.redhat.com/errata/RHSA-2026:95755

https://access.redhat.com/errata/RHSA-2026:95745

https://access.redhat.com/errata/RHSA-2026:95508

https://access.redhat.com/errata/RHSA-2026:89333

https://access.redhat.com/errata/RHSA-2026:89232

https://access.redhat.com/errata/RHSA-2026:89197

https://access.redhat.com/errata/RHSA-2026:82888

https://access.redhat.com/errata/RHSA-2026:82857

https://access.redhat.com/errata/RHSA-2026:82372

https://access.redhat.com/errata/RHSA-2026:82354

https://access.redhat.com/errata/RHSA-2026:82347

https://access.redhat.com/errata/RHSA-2026:82322

https://access.redhat.com/errata/RHSA-2026:82304

https://access.redhat.com/errata/RHSA-2026:74674

https://access.redhat.com/errata/RHSA-2026:72502

https://access.redhat.com/errata/RHSA-2026:60019

https://access.redhat.com/errata/RHSA-2026:59831

https://access.redhat.com/errata/RHSA-2026:58981

https://access.redhat.com/errata/RHSA-2026:57483

https://access.redhat.com/errata/RHSA-2026:56853

https://access.redhat.com/errata/RHSA-2026:43575

https://access.redhat.com/errata/RHSA-2026:41921

https://access.redhat.com/errata/RHSA-2026:40762

https://access.redhat.com/errata/RHSA-2026:33125

https://access.redhat.com/errata/RHSA-2026:32962

https://access.redhat.com/errata/RHSA-2026:30850

https://access.redhat.com/errata/RHSA-2026:30849

https://access.redhat.com/errata/RHSA-2026:30004

https://access.redhat.com/errata/RHSA-2026:29197

https://access.redhat.com/errata/RHSA-2026:26409

https://access.redhat.com/errata/RHSA-2026:26319

https://access.redhat.com/errata/RHSA-2026:20613

https://access.redhat.com/errata/RHSA-2026:20612

https://access.redhat.com/errata/RHSA-2026:20611

https://access.redhat.com/errata/RHSA-2026:13274

Details

Source: Mitre, NVD

Published: 2026-05-26

Updated: 2026-11-11

Risk Information

CVSS v2

Base Score: 8.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:C/A:N

Severity: High

CVSS v3

Base Score: 8.2

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

Severity: High

EPSS

EPSS: 0.00423