misc.php for vBulletin 3.0.6 and earlier, when "Add Template Name in HTML Comments" is enabled, allows remote attackers to execute arbitrary PHP code via nested variables in the template parameter.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2005-0512
http://www.vbulletin.com/forum/showthread.php?postid=819562
http://www.securityfocus.com/bid/12622