How to Fix a Contacts App Crashing Glitch on iOS 6.1.x
You may, or may not have known this, but there’s a glitch in iOS 6.1.x that can cause your Contacts application to crash unexpectedly.
The bug happens when you’re in grid view in the Photos application, you tap on the edit button, then hold down on one of the photograph thumbnails from the grid and copy the photograph. After you do so, and you open the Contacts application, edit a contact, hold down on the contact’s photo field and try to paste the photograph you copied, the Contacts application will just crash on you.
A new free jailbreak tweak called Contact Fix for 6.1.x
by iOS developer yeahwangy is available in Cydia as of Wednesday afternoon that fixes the problem and keeps the Contacts application from crashing when you change a contact’s picture in the way explained above.
There are also alternative ways to set contact pictures that won’t crash the Contacts application on iOS 6.1.x; however, it’s reassuring to see the jailbreak community coming up with homebrew fixes for Apple’s errors. The bug doesn't appear to be present on pre-iOS 6.1.x firmwares, so you'll need to be on an iOS 6.1.x firmware to install the tweak.
Contact Fix for 6.1.x