People logging in to Macs running OS X 10.7, aka Lion, can access restricted resources using any password they want when the machines use a popular technology known as LDAP for authentication. Short for Lightweight Directory Access Protocol, LDAP servers frequently contain repositories of highly sensitive enterprise data, making them a goldmine to attackers trying to burrow their way in to sensitive networks.
http://www.theregister.co.uk/2011/08/26/ma..._security_hole/