iOS 11.3.1 improves the security of your iPhone or iPad and addresses an issue where touch input was unresponsive on some iPhone 8 devices because they were serviced with non-genuine replacement displays.

Note: Non-genuine replacement displays may have compromised visual quality and may fail to work correctly. Apple-certified screen repairs are performed by trusted experts who use genuine Apple parts. See support.apple.com for more information.

For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222