CVE-2026-3833
Publication date 30 April 2026
Last updated 6 July 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| gnutls28 | 26.10 stonking |
Not affected
|
| 26.04 LTS resolute |
Fixed in 3.8.12-2ubuntu1.1
|
|
| 24.04 LTS noble |
Fixed in 3.8.3-1.1ubuntu3.6
|
|
| 22.04 LTS jammy |
Fixed in 3.7.3-4ubuntu1.9
|
|
| 20.04 LTS focal |
Fixed in 3.6.13-2ubuntu1.12+esm2
|
|
| 18.04 LTS bionic |
Fixed in 3.5.18-1ubuntu1.6+esm3
|
|
| 16.04 LTS xenial |
Fixed in 3.4.10-4ubuntu1.9+esm3
|
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CVSS version: CVSS v3.0
Base score
6.5 · Medium
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
References
Related Ubuntu Security Notices (USN)
- USN-8284-1
- GnuTLS vulnerabilities
- 20 May 2026
- USN-8502-1
- GnuTLS vulnerabilities
- 6 July 2026