An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, tvOS 14.3, macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave, iOS 14.3 and iPadOS 14.3, watchOS 7.2. A remote attacker may be able to leak memory.
https://support.apple.com/en-us/HT212147
https://support.apple.com/en-us/HT212011
https://support.apple.com/en-us/HT212009