CVE-2026-91769

PHP's OpenSSL stream peer verification checks the certificate's subjectAltName entries first and, whenever no entry matches, falls back to the Common Name. RFC 6125 requires the CN to be ignored once the certificate presents any service identity, so a certificate carrying a non-matching DNS SAN was still accepted when its CN matched the requested peer_name. A certificate trusted by the client for one name can therefore be used to impersonate another.

Score

CVSS 3.1 4.3 Medium

Status

Analyzed - security@php.net

Published

2026-09-25

Last modified

2026-10-23

Weaknesses

CWE-297

Affected products

• Php (Php)
• Php (Php Group)

References

• https://github.com/php/php-src/security/advisories/GHSA-vvx9-73fr-5jjx