CVE-2026-91769

Summary

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.

Affected Software

VendorProductVersion RangeStatus
PHP GroupPHP8.2.* < 8.2.34affected
PHP GroupPHP8.3.* < 8.3.35affected
PHP GroupPHP8.4.* < 8.4.26affected
PHP GroupPHP8.5.* < 8.5.11affected

Weaknesses

  • CWE-297: CWE-297 Improper validation of certificate with host mismatch

References