Race condition in LoginUIFramework in Apple Mac OS X 10.7.x before 10.7.4, when the Guest account is enabled, allows physically proximate attackers to login to arbitrary accounts by entering the account name and no password.
Concurrent Execution using Shared Resource with Improper Synchronization The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.