A memory corruption issue was addressed with improved state management. This issue is fixed in macOS Ventura 13.3, Safari 16.4, iOS 16.4 and iPadOS 16.4, iOS 15.7.7 and iPadOS 15.7.7. Processing web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited against versions of iOS released before iOS 15.7.
https://storage.googleapis.com/gweb-uniblog-publish-prod/documents/Year_in_Review_of_ZeroDays.pdf
https://thehackernews.com/2023/12/most-sophisticated-iphone-hack-ever.html
https://support.apple.com/en-us/HT213811
https://support.apple.com/en-us/HT213676