A security flaw in Apple's iOS 6.1 lets anyone bypass your iPhone password lock and access your phone app, view or modify contacts, check your voicemail, and look through your photos (by attempting to add a photo to a contact). The method, as detailed by YouTube user videosdebarraquito, involves making (and immediately canceling) an emergency call and holding down the power button twice. We followed the steps and managed to access the phone app on two UK iPhone 5s running iOS 6.1. This isn't the first time this has happened — a very similar bug affected iOS 4.1, and was fixed in iOS 4.2. We've reached out to Apple for comment and will update you once we hear back.
Update: Apple says it is aware of the issue and is currently working on a fix that will be deployed in a future software update.