A path handling issue was addressed with improved validation. This issue is fixed in macOS Big Sur 11.0.1, iOS 14.2 and iPadOS 14.2, tvOS 14.2, watchOS 7.1. A local attacker may be able to elevate their privileges.
http://seclists.org/fulldisclosure/2020/Dec/26
http://seclists.org/fulldisclosure/2020/Dec/32
https://support.apple.com/en-us/HT211928
https://support.apple.com/en-us/HT211929
https://support.apple.com/en-us/HT211930