New passcode flaw discovered in Apple iPhone 4 and Apple iPhone 5 running iOS 6.1.3
The series of steps required includes making a Voice Dial command followed by the quick ejection of the SIM card on the phone. This opens the recent call history which gives access to the contacts list. While in the contacts list, adding a photo brings access to all pictures on the unit. A simple disabling of the Voice Dialer from the Passcode Lock menu will eliminate the security hazard although we're sure that Apple will send out a fix in iOS 6.1.4.
source: iPhoneblog.de (translated), MacRumors