An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.0, tvOS 14.0, iOS 14.0 and iPadOS 14.0. A malicious application may be able to read restricted memory.
http://seclists.org/fulldisclosure/2020/Dec/26
http://seclists.org/fulldisclosure/2020/Dec/32
https://support.apple.com/en-us/HT211843
https://support.apple.com/en-us/HT211844
https://support.apple.com/en-us/HT211850