A new bug in the Apple iOS 12.1 update has been found, allowing contact information to be accessed without going through the lockscreen. The discovery was made pretty soon after the update went live earlier this week.
This exploit only works with iOS 12.1, and involves making a group FaceTime call, which will bring up your contact list without a need for a passcode. From there, you can use 3D Touch to get more info on each contact.
The video below also demonstrates that, while the call is going on, it is possible to engage Airplane mode to get more time to go through the details of each contact.
For what it’s worth, this exploit requires physical access to the device in question. So in a way, your iPhone is safe provided you carry it with you at all times and you don’t have leave it lying around.