https://www.bleepingcomputer.com/news/apple/apple-backports-fix-for-rtkit-ios-zero-day-to-older-iphones/

Apple has backported security patches released in March to older iPhones and iPads, fixing an iOS Kernel zero-day tagged as exploited in attacks.

In security advisories published today, Apple once again said they're aware of reports that this vulnerability "may have been actively exploited."