An issue was discovered in openfortivpn 1.11.0 when used with OpenSSL before 1.0.2. tunnel.c mishandles certificate validation because hostname comparisons do not consider '\0' characters, as demonstrated by a good.example.com\x00evil.example.com attack.

An issue was discovered in openfortivpn 1.11.0 when used with OpenSSL 1.0.2 or later. tunnel.c mishandles certificate validation because the hostname check operates on uninitialized memory. The outcome is that a valid certificate is never accepted (only a malformed certificate may be accepted).

An issue was discovered in openfortivpn 1.11.0 when used with OpenSSL 1.0.2 or later. tunnel.c mishandles certificate validation because an X509_check_host negative error code is interpreted as a successful return value.