A memory corruption issue was addressed with improved memory handling. This issue is fixed in macOS Catalina 10.15, iOS 13.1 and iPadOS 13.1, tvOS 13, macOS Catalina 10.15.1, Security Update 2019-001, and Security Update 2019-006, watchOS 6. An application may be able to execute arbitrary code with system privileges.
https://support.apple.com/en-us/HT210722
https://support.apple.com/en-us/HT210634
https://support.apple.com/en-us/HT210607