EUVD-2026-87913

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...

Linux Distros Unpatched Vulnerability : CVE-2026-6731

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - X.509 name constraint bypass via the Subject Common Name when treated as a DNS-type name. A certificate whose Subject CN violates an issuing CA's DNS name...

UBUNTU-CVE-2026-6731

X.509 name constraint bypass via the Subject Common Name when treated as a DNS-type name. A certificate whose Subject CN violates an issuing CA's DNS name constraints could be accepted...

CVE-2026-6731

CVE-2026-6731 describes an X.509 name constraint bypass where the Subject CN is treated as a DNS-type name, allowing a certificate to pass DNS constraints if the CN violates them. Public sources (NVD and related feeds) reference this bypass and provide CVSS metrics (v3.1: 7.5, Network, High impac...