A validation issue was addressed with improved logic. This issue is fixed in Safari 13.0.1, iOS 13.1 and iPadOS 13.1, iCloud for Windows 10.7, tvOS 13, iCloud for Windows 7.14, iTunes 12.10.1 for Windows. Processing maliciously crafted web content may lead to universal cross site scripting.
https://support.apple.com/en-us/HT210637
https://support.apple.com/en-us/HT210636
https://support.apple.com/en-us/HT210635
https://support.apple.com/en-us/HT210605