The vulnerability, which was highlighted on Monday by Jacqui Cheng of Ars Technica, is similar to one that was recently discovered. But the new exploit can make the iPhone screen go black, and allow an attacker to plug in the device to a computer via USB and potentially access the data stored on the handset.
Like the previous hack, the exploit can be accessed by making and then immediately canceling an emergency call on a passcode-locked device.
Of course, a hacker must have physical access to the device for the exploit to yield any data. But using the method highlighted, data such as contacts and voicemails could be extracted from a stolen iPhone even if a passcode lock were enabled on the device.
The previously highlighted lockscreen bug will be addressed by Apple in a forthcoming software update. A beta version of iOS 6.1.3 that addresses the issue was supplied by Apple to developers for testing last week.
Apple's iOS platform has had a history of lockscreen passcode bugs, as Cheng noted issues have existed in iOS 2.0, iOS 4.1, and now iOS 6.1.