source: http://www.securityfocus.com/bid/18197/info

vBulletin is prone to an SQL-injection vulnerability. This issue is due to a failure in the application to properly sanitize user-supplied input before using it in an SQL query. 

A successful exploit could allow an attacker to compromise the application, access or modify data, or exploit vulnerabilities in the underlying database implementation.

http://www.example.com/portal.php?id=54&a=viewfeature&featureid=99999/**/UNION/**/SELECT/**/0,1,2,3,4,username,6,7,8,9,10,11,12,password/**/from/**/user/**/where/**/userid=1/*