CVE-2026-42013 PUBLISHED

Gnutls: gnutls: certificate validation bypass due to oversized subject alternative name

Assigner: redhat
Reserved: 23.04.2026 Published: 26.05.2026 Updated: 27.05.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
CVSS Score: 8.2

Product Status

Vendor Red Hat
Product Red Hat Enterprise Linux 8
Versions Default: affected
  • unaffected from 0:3.6.16-8.el8_10.6 to * (excl.)
Vendor Red Hat
Product Red Hat Enterprise Linux 8
Versions Default: affected
  • unaffected from 0:3.6.16-8.el8_10.6 to * (excl.)
Vendor Red Hat
Product Red Hat Enterprise Linux 10
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 6
Versions Default: unknown
Vendor Red Hat
Product Red Hat Enterprise Linux 7
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 9
Versions Default: affected
Vendor Red Hat
Product Red Hat Hardened Images
Versions Default: affected
Vendor Red Hat
Product Red Hat OpenShift Container Platform 4
Versions Default: affected

Credits

  • Red Hat would like to thank Haruto Kimura (Stella) and Joshua Rogers (AISLE Research Team) for reporting this issue.

References

Problem Types

  • Improper Validation of Specified Quantity in Input CWE