Passcode Lock in Apple iOS before 7.0.2 does not properly manage the lock state, which allows physically proximate attackers to bypass an intended passcode requirement, and open the Camera app or read the list of all recently opened apps, by leveraging unspecified transition errors.
http://support.apple.com/kb/HT5957
http://lists.apple.com/archives/security-announce/2013/Sep/msg00009.html