🛡️ CVE-2026-42013 on Debian — gnutls28

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.

Distribution advisory

This page covers CVE-2026-42013 as tracked by Debian, for the package gnutls28. The fix is available in version 3.8.13-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity high, availability none.

Weakness class

DEBIAN-CVE-2026-42013 is classified as CWE-295: Improper Certificate Validation. A TLS certificate is accepted without proper verification, so a man-in-the-middle can present their own.

Affected software

DEBIAN-CVE-2026-42013 is recorded against 1 package.

  • gnutls28 (fixed in 3.8.13-1)

Timeline and source

Published on 26 May 2026 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2026-42013 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-05-26
Updated 2026-08-20
Modified 2026-08-04
Fix URL N/A

Affected Packages

Software From version Fixed in
gnutls28 — 3.8.13-1

Site Security Check

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DEBIAN-CVE-2026-42013 is rated CVSS 8.2 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

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