Today Apple has started to roll out iOS 11.2.1 for eligible device across the globe and it weighs around 60MB. This update brings fixes the inability to use remote access in Home Kit for shared users.
This was temporarily disabled last week through a server-side switch, in order to swiftly address a newly discovered vulnerability in Apple’s smart home framework, which allowed unauthorized access to occur in certain conditions. After update you will be able to access the Apple smart-home.
According to the change logs the update does not bring any security related changes/fixes. Apple also released update to it Apple TV – tvOS 11.2.1. If the update is not shown, please head to Settings -> General -> Software update