A logic issue was addressed with improved state management. This issue is fixed in iTunes 12.11.3 for Windows, Security Update 2021-002 Catalina, Security Update 2021-003 Mojave, iCloud for Windows 12.3, macOS Big Sur 11.3, watchOS 7.4, tvOS 14.5, iOS 14.5 and iPadOS 14.5. Processing a maliciously crafted font may result in the disclosure of process memory.
https://support.apple.com/en-us/HT212327
https://support.apple.com/en-us/HT212326
https://support.apple.com/en-us/HT212325
https://support.apple.com/en-us/HT212324
https://support.apple.com/en-us/HT212323
https://support.apple.com/en-us/HT212321