A use after free issue was addressed with improved memory management. 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. Processing maliciously crafted web content may lead to code execution.
https://support.apple.com/HT211101
https://support.apple.com/HT211102
https://support.apple.com/HT211104
https://support.apple.com/HT211105