CVE-2026-88647: Critical severity GNUTLS GNUTLS vulnerability
A hostname verification bypass in GnuTLS v3.8.13 allows attackers to circumvent the Common Name fallback mechanism and eavesdrop on communications via a crafted certificate.
Other sources
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.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What does an attacker need to exploit this issue?
An attacker needs to present a crafted certificate in a position where they can eavesdrop on or intercept the affected TLS communications.
What type of traffic is at risk?
TLS communications using GnuTLS 3.8.13 are at risk when hostname verification relies on the Common Name fallback mechanism.