The Lock Screen component in Apple iOS before 8.3 does not properly enforce the limit on incorrect passcode-authentication attempts, which makes it easier for physically proximate attackers to obtain access by making many passcode guesses.
https://support.apple.com/HT204661
http://www.securitytracker.com/id/1032050
http://www.securityfocus.com/bid/73978
http://lists.apple.com/archives/security-announce/2015/Apr/msg00002.html