A race condition was addressed with additional validation. This issue is fixed in iOS 13.4 and iPadOS 13.4, tvOS 13.4, Safari 13.1, iTunes for Windows 12.10.5, iCloud for Windows 10.9.3, iCloud for Windows 7.18. An application may be able to read restricted memory.
https://support.apple.com/HT211107
https://support.apple.com/HT211106
https://support.apple.com/HT211105
https://support.apple.com/HT211104