A use after free issue was addressed with improved memory management. This issue is fixed in macOS Big Sur 11.0.1, watchOS 7.1, iOS 14.2 and iPadOS 14.2, iCloud for Windows 11.5, tvOS 14.2, iTunes 12.11 for Windows. Processing maliciously crafted web content may lead to code execution.
https://support.apple.com/en-us/HT211935
https://support.apple.com/en-us/HT211933
https://support.apple.com/en-us/HT211931
https://support.apple.com/en-us/HT211930
https://support.apple.com/en-us/HT211929