JLSEC-2026-755 X.509 name constraint bypass via the Subject Common Name when treated as a DNS-type name

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...

USN-8539-1: GnuTLS vulnerabilities

Haruto Kimura discovered that GnuTLS did not properly apply permitted name constraints in certain certificate validation paths. A remote attacker could possibly use this issue to bypass certificate validation, leading to a machine-in-the-middle attack. CVE-2026-42011 Oleh Konko discovered that...

PYSEC-2026-665 Mercurial Improper Certificate Validation vulnerability

Mercurial before 1.6.4 fails to verify the Common Name field of SSL certificates which allows remote attackers who acquire a certificate signed by a Certificate Authority to perform a man-in-the-middle attack...

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...

gnutls: gnutls: Certificate validation bypass due to improper handling of URI and SRV SANs

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...

gnutls: gnutls: Certificate validation bypass due to oversized Subject Alternative Name

A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name SAN could cause the validation process to incorrectly fall back to checking the Common Name CN field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to...

gnutls: gnutls: Certificate validation bypass due to oversized Subject Alternative Name

A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name SAN could cause the validation process to incorrectly fall back to checking the Common Name CN field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to...

gnutls: gnutls: Certificate validation bypass due to oversized Subject Alternative Name

A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name SAN could cause the validation process to incorrectly fall back to checking the Common Name CN field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to...

gnutls: gnutls: Certificate validation bypass due to improper handling of URI and SRV SANs

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...

gnutls: gnutls: Certificate validation bypass due to oversized Subject Alternative Name

A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name SAN could cause the validation process to incorrectly fall back to checking the Common Name CN field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to...

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...

DEBIAN-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

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...

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

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 X.509 name constraint bypass via Subject CN treated as a DNS name

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...

EUVD-2026-39555

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

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...

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...