CVE-2026-89134: wolfSSL

Critical severity, CVSS 9.1. EPSS: 0.2% chance of exploitation in the next 30 days.

A certificate with no dNSName SAN but another SAN type present (e.g. registeredID or iPAddress) bypassed the Subject CN dNSName name-constraint check. The CN-as-DNS fallback was gated on cert->subjectCN != NULL && cert->altNames == NULL && !cert->isCA instead of "no dNSName SAN", so an out-of-scope CN was accepted. This incomplete fix from CVE-2026-6731, leading to the name-constraint check issue, was introduced in wolfSSL version 5.9.2.

Affected products

• wolfSSL wolfSSL: version 5.9.2 only

Published 2026-09-27. Last modified 2026-10-02.