Apple has issued an iOS update. Users are encouraged to install this update as it fixes several security issues.
The update applies to iPhone 6s and later, iPad Pro (all models), iPad Air 2 and later, iPad 5th generation and later, iPad mini 4 and later, and iPod touch (7th generation).
The WebKit fixes impact “maliciously crafted web content [that] may lead to arbitrary code execution.”
There are various updates to other Mac and Watch OS devices as well. As with any update, you should make a backup first.