A validation issue existed in the handling of symlinks. This issue was addressed with improved validation of symlinks. This issue is fixed in Security Update 2021-004 Mojave, iOS 14.6 and iPadOS 14.6, Security Update 2021-003 Catalina, macOS Big Sur 11.4, watchOS 7.5. A malicious application may be able to gain root privileges.
https://support.apple.com/en-us/HT212533
https://support.apple.com/en-us/HT212531
https://support.apple.com/en-us/HT212530