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.
https://bugzilla.redhat.com/show_bug.cgi?id=2445763
https://access.redhat.com/security/cve/CVE-2026-3833
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