A double free issue was addressed with improved memory management. This issue is fixed in tvOS 14.6, iOS 14.6 and iPadOS 14.6, Security Update 2021-004 Catalina, Security Update 2021-005 Mojave, macOS Big Sur 11.4, watchOS 7.5. An application may be able to execute arbitrary code with kernel privileges.
https://support.apple.com/en-us/HT212603
https://support.apple.com/en-us/HT212600
https://support.apple.com/en-us/HT212533
https://support.apple.com/en-us/HT212532