Cross-site scripting (XSS) vulnerability in vBulletin 3.0.12 and 3.5.3 allows remote attackers to inject arbitrary web script or HTML via the email field, which is injected in profile.php but not sanitized in sendmsg.php.
http://www.vupen.com/english/advisories/2006/0808
http://www.vbulletin.com/forum/showthread.php?postid=1079030
http://www.securityfocus.com/bid/16919
http://www.securityfocus.com/archive/1/426589/100/0/threaded
http://www.securityfocus.com/archive/1/426537/100/0/threaded