source: https://www.securityfocus.com/bid/27471/info

ClanSphere is prone to a local file-include vulnerability because it fails to properly sanitize user-supplied input.

An attacker can exploit this vulnerability using directory-traversal strings to access potentially sensitive information that may aid in further attacks.

ClanSphere 2007.4.4 is vulnerable to this issue; other versions may also be affected. 

http://www.example.com/install.php?lang=..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2F..%2Fetc%2Fpasswd%00