admin.php3 in PHP-Nuke does not properly verify the PHP-Nuke administrator password, which allows remote attackers to gain privileges by requesting a URL that does not specify the aid or pwd parameter.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2000-0740
http://www.securityfocus.com/bid/1592
http://archives.neohapsis.com/archives/bugtraq/2000-08/0243.html