Race condition in Login Window in Apple Mac OS X 10.5 through 10.5.4, when a blank-password account is enabled, allows attackers to bypass password authentication and login to any account via multiple attempts to login to the blank-password account, followed by selection of an arbitrary account from the user list.
https://exchange.xforce.ibmcloud.com/vulnerabilities/45170
http://www.vupen.com/english/advisories/2008/2584
http://www.us-cert.gov/cas/techalerts/TA08-260A.html
http://www.securityfocus.com/bid/31189
http://securitytracker.com/id?1020878
http://secunia.com/advisories/31882
http://lists.apple.com/archives/security-announce//2008/Sep/msg00005.html