Advanced Guestbook 2.2 and 2.3.1 and possibly other versions suffer from XSS
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/42680/AdvGuestbookXSS.txt
Source: https://packetstormsecurity.com/files/42680/AdvGuestbookXSS.txt.html