An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in iOS 15.1 and iPadOS 15.1, macOS Monterey 12.0.1, tvOS 15.1, watchOS 8.1, Security Update 2021-007 Catalina. Processing a maliciously crafted file may disclose user information.
https://www.zerodayinitiative.com/advisories/ZDI-21-1368/
https://support.apple.com/kb/HT212872
https://support.apple.com/kb/HT212807
https://support.apple.com/en-us/HT212876
https://support.apple.com/en-us/HT212874
https://support.apple.com/en-us/HT212871