Hostname Verif Bypass in GnuTLS 3.8.13 (CN Fallback)
CVE-2026-88647 Published on October 8, 2026
GnuTLS v3.8.13 can perhaps unexpectedly trust a certificate on the basis of Common Name when Subject Alternative Name has an SRV otherName (1.3.6.1.5.5.7.8.7) whose value is an OCTET STRING. NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.
Vulnerability Analysis
CVE-2026-88647 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a high impact on integrity, and no impact on availability.
Weakness Type
Improper Validation of Certificate with Host Mismatch
The software communicates with a host that provides a certificate, but the software does not properly ensure that the certificate is actually associated with that host.
Products Associated with CVE-2026-88647
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