CVE-2026-3833: GNU Gnutls

High severity, CVSS 7.4. EPSS: 0.9% chance of exploitation in the next 30 days.

A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.

Affected products

• GNU Gnutls: affected versions not specified
• Red Hat Enterprise Linux: version 6.0 only; version 7.0 only; version 8.0 only; version 9.0 only; version 10.0 only
• Red Hat Hardened Images: affected versions not specified
• Red Hat Openshift Container Platform: version 4.0 only

Published 2026-04-30. Last modified 2026-10-09.