source: https://www.securityfocus.com/bid/8520/info

It has been reported that TSguestbook may be prone to HTML injection attacks. The problem is said to occur due to insufficient sanitization of user-supplied input within the 'message' field. As a result, an attacker may post a guestbook entry including malicious HTML or script code within the said field. This could result in the execution of arbitrary code within the browser of an unsuspecting guestbook user. 

Name: Zone-h Security Team

Email: test@test.com

ICQ: 11111111

Homepage: http://www.zone-h.org

Message:<script>alert('Zone-H')</script>