Improper Handling of Case Sensitivity Affecting gnutls28 package, versions <3.6.13-2ubuntu1.12+esm2


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.56% (44th percentile)

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  • Snyk IDSNYK-UBUNTU2004-GNUTLS28-16355158
  • published7 Jul 2026
  • disclosed30 Apr 2026

Introduced: 30 Apr 2026

CVE-2026-3833  (opens in a new tab)
CWE-178  (opens in a new tab)

How to fix?

Upgrade Ubuntu:20.04 gnutls28 to version 3.6.13-2ubuntu1.12+esm2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream gnutls28 package and not the gnutls28 package as distributed by Ubuntu. See How to fix? for Ubuntu:20.04 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1