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.
CWE-287 - Improper Authentication
Improper (or broken) authentication attacks are widespread, and have accounted for many of the worst data breaches in recent years. Improper authentication attacks are a class of vulnerabilities where an attacker impersonates a legitimate user by exploiting weaknesses in either session management or credential management to gain access to the user’s account. This can result in disclosure of sensitive information, and can lead to system compromise, theft, identity theft, and fraud.