PHP remote file inclusion vulnerability in install/upgrade_301.php in Jelsoft vBulletin 3.5.4 allows remote attackers to execute arbitrary PHP code via a URL in the step parameter. NOTE: the vendor has disputed this vulnerability, saying "The default vBulletin requires authentication prior to the usage of the upgrade system.
http://www.pldsoft.com/forum/showthread.php?t=1340
http://archives.neohapsis.com/archives/bugtraq/2006-07/0217.html
http://archives.neohapsis.com/archives/bugtraq/2006-07/0121.html
http://archives.neohapsis.com/archives/bugtraq/2006-07/0069.html