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.