CVE-2026-3833

MEDIUM

Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison

Title source: cna
STIX 2.1

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.

References (7)

Core 7
Core References
Vendor Advisory vendor-advisory x_refsource_redhat
RHSA-2026:20612
https://access.redhat.com/errata/RHSA-2026:20612
Vendor Advisory vendor-advisory x_refsource_redhat
https://access.redhat.com/errata/RHSA-2026:20613
Vendor Advisory vendor-advisory x_refsource_redhat
RHSA-2026:13274
https://access.redhat.com/errata/RHSA-2026:13274
Vdb Entry, X_Refsource_Redhat vdb-entry x_refsource_redhat
https://access.redhat.com/security/cve/CVE-2026-3833
Vendor Advisory vendor-advisory x_refsource_redhat
RHSA-2026:20611
https://access.redhat.com/errata/RHSA-2026:20611
Issue Tracking, X_Refsource_Redhat issue-tracking x_refsource_redhat
RHBZ#2445763
https://bugzilla.redhat.com/show_bug.cgi?id=2445763

Scores

CVSS v3 6.5
EPSS 0.0032
EPSS Percentile 23.5%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-178
Status published
Products (19)
gnu/gnutls
Red Hat/Red Hat Enterprise Linux 10
Red Hat/Red Hat Enterprise Linux 10 0:3.8.10-4.el10_2
Red Hat/Red Hat Enterprise Linux 6
Red Hat/Red Hat Enterprise Linux 7
Red Hat/Red Hat Enterprise Linux 8
Red Hat/Red Hat Enterprise Linux 8 0:3.6.16-8.el8_10.6
Red Hat/Red Hat Enterprise Linux 9
Red Hat/Red Hat Enterprise Linux 9 0:3.8.10-4.el9_8
Red Hat/Red Hat Hardened Images
... and 9 more
Published Apr 30, 2026
Tracked Since Apr 30, 2026