CVE intelligence and bounded remediation
CVE-2026-42012 — A flaw was found in gnutls
A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted certificate that contains Uniform Resource Identifier (URI) or Service (SRV) Subject Alternative Names (SANs). This could cause the certificate validation process to incorrectly fall back to checking DNS hostnames against the Common Name (CN), potentially allowing the attacker to spoof legitimate services or intercept sensitive information.
- Severity
- High
- CVSS
- 7.1 (3.1)
- Published
- 2026-05-26
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-295
Affected products
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Matched remediation archetype
Cryptography, certificate, signature, and channel validation
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Inventory affected algorithms, key uses, trust stores, certificate validation settings, random sources, and plaintext channels across clients and services.
- Determine which secrets, identities, signatures, or data protections depend on the affected primitive or validation path.
- Check debug, compatibility, fallback, and hostname or audience override settings in build and runtime configuration.
Remediate safely
- Use a maintained platform cryptographic API with approved algorithms, modes, parameters, randomness, and full peer identity validation.
- Remove insecure fallback and validation bypasses; separate keys by purpose and load them from managed secret storage.
- Plan rotation or reissuance for affected keys, certificates, tokens, hashes, or ciphertext and document compatibility sequencing.
Authoritative sources
Complete CVE record and remediation plan
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