Apple just rolled out a new update for iPhones and iPads.
IOS 11.2.1 is important to apply, specifically if you have a smart home that uses a HomeKit-enabled smart lock. A vulnerability in iOS 11.2 makes it possible for hackers to potentially take advantage of the bug to unlock a smart lock that was connected to HomeKit. In other words, an educated hacker could have potentially unlocked your front door.
That's patched in iOS 11.2.1, which is rolling out now. You can get it by going to Settings > General > Software Update.