CVE-2026-3833 Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison
Attackers can bypass certificate name constraints by exploiting case-sensitive comparisons in GnuTLS, leading to unauthorized access or information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-3833?
CVE-2026-3833 is a medium-severity vulnerability in Gnu Gnutls, published on 30 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-178
Which versions are affected by CVE-2026-3833?
It affects 4 products.
Products include Gnu Gnutls, Redhat Enterprise Linux, Redhat Hardened Images, Redhat Openshift Container Platform.
How do I fix CVE-2026-3833?
Apply the vendor's patch.
Is CVE-2026-3833 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-3833 exists.
Other vulnerabilities in Gnu Gnutls
Sources
Also known as ALPINE-CVE-2026-3833, BELL-CVE-2026-3833, CLSA-2026-1778832314, CLSA-2026-1778835563, CLSA-2026-1778839424, CLSA-2026-1779107085 and 10 more.