Just discovered this loophole that appears to only affect the iPhone 5s with Touch ID enabled. If you open Siri and have it show you a restaurant, you can tap through to the photos from Yelp and by tapping on a photo, it will simply launch Yelp or the App Store, letting you press the home button and gaining access to the whole phone. I tried this on a 5, and when I would tap on the photo, the pass code entry popped up, blocking access. This is pretty serious, since it gives you complete access to the phone and not just contacts or photos. If more can confirm this, Apple should fix it ASAP.