The issue was addressed with improved handling of caches. This issue is fixed in tvOS 16.3, iOS 16.3 and iPadOS 16.3, macOS Monterey 12.6.8, macOS Big Sur 11.7.9, iOS 15.7.8 and iPadOS 15.7.8, macOS Ventura 13.2, watchOS 9.3. Processing a font file 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 15.7.1.
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/HT213845
https://support.apple.com/en-us/HT213844
https://support.apple.com/en-us/HT213842
https://support.apple.com/en-us/HT213606
https://support.apple.com/en-us/HT213605