Apple has released a security update to combat recently uncovered security issues.
The security update (iOS 11.2.2) was released overnight for both the iPhone and iPad, and Apple recommends the update "for all users". There are also separate updates for macOS and the Safari web broswer.
The update comes after Apple last week acknowledged the recently discovered Meltdown and Spectre CPU security vulnerabilities affected all Mac and iOS systems.
You can find out more information on how to update your device here.