Its a recently discovered known security issue in iOS6 that can enable you to bypass iPhone lock screen without having to enter the actual password. This is useful in case you forgot your iPhone password but its a serious issue if your iPhone gets to the wrong hands.
No operating system / code is free of bugs completely. It takes time for software developers to figure out and answer those bugs. And when these known bugs are answered, someone finds out another security loop hole in the system. Then software has to be updated to the new version. Story is same for the Apple iOS. iPhone4 users faced unexpected battery drainage. iOS devices also have issues with setting automatic brightness levels. Problem in network signal was reported a while back. Now new issues in iOS6 have been reported by Apple users. Here is the trick that can bypass the iPhone lock screen on iOS6 and access iPhone contacts.
Ultrasn0w 1.2.3 has been released to make the unlock compatible with iOS 4.3.3 on iPhone 4 and 3GS, running on the old baseband. This release of Ultrasn0w is not a new unlock for iPhones with newer basebands, instead, it only fixes the compatibility issues on the existing devices, which are jailbroken (with preserved basebands: 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00) on iOS 4.3.3. Updating iPhone 3GS baseband to iPad’s 06.15.00 might result in loss of GPS functionality. Proceed to the step by step guide to unlock iOS 4.3.3 on iPhone 4, 3GS Using Ultrasn0w 1.2.3.