Vulnerability Details CVE-2026-91767
php_openssl_matches_wildcard_name() in ext/openssl/xp_ssl.c underflows the length argument passed to memchr() when a TLS server certificate presents a wildcard name whose literal characters are together longer than the hostname being verified. A malicious server presenting such a certificate makes the PHP client read up to SIZE_MAX bytes past the end of a heap allocation. The path is reachable from any default client stream, because verify_peer_name is enabled by default.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 1.1%
CVSS Severity
CVSS v3 Score 6.5