It took less than 24 hours for someone to find a way to break through iOS 7's passcode feature, and wouldn't you know it: the new Control Center is to blame. By going through a rather simple series of swipes and taps, a user can bypass the lock screen on some iOS 7 devices. You start in the Control Center, switch to the Timer, then double-tap the home button which lets you access the multitasking feature, allowing you to browse apps without having to unlock the device.
I say "some" because there's a rather simple tweak you can perform that will prevent someone from using this nasty trick on your own iPhone or iPad: Simply go to Settings -> Control Center and toggle the "Access on Lock Screen" option to "off." Ta-da! You're safe!
Update: Apple is working on a fix.
Update 2: According to multiple reports, accessing the multitasking menu through the Timer glitch only produces blank screenshots, but using the glitch while in the Camera app gets the job done.