CVE-2026-42013: Improper Certificate Validation
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.
CVE-2026-42013: Improper Certificate Validation
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.
CVSS v3.1
Score 8.2high
Affected software
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-2pw7-g86g-76q7
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-42013"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a6151299c2644c7f8da6843
Added to database: 07/22/2026, 23:24:25 UTC
Last enriched: 08/21/2026, 14:55:34 UTC
Last updated: 09/10/2026, 21:01:36 UTC
Views: 116
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.