A type confusion issue was addressed with improved memory handling. This issue is fixed in iOS 14.8 and iPadOS 14.8, tvOS 15, watchOS 8, iOS 15 and iPadOS 15. Processing maliciously crafted web content may lead to arbitrary code execution.
https://support.apple.com/kb/HT212953
https://support.apple.com/kb/HT212869
https://support.apple.com/en-us/HT212819
https://support.apple.com/en-us/HT212815