An input validation issue was addressed with improved input validation. This issue is fixed in iOS 14.0 and iPadOS 14.0, tvOS 14.0, watchOS 7.0, Safari 14.0, iCloud for Windows 11.4, iCloud for Windows 7.21. Processing maliciously crafted web content may lead to a cross site scripting attack.
https://support.apple.com/HT211850
https://support.apple.com/HT211847
https://support.apple.com/HT211846
https://support.apple.com/HT211845
https://support.apple.com/HT211844
https://support.apple.com/HT211843
https://security.gentoo.org/glsa/202012-10
http://www.openwall.com/lists/oss-security/2020/11/23/3
http://seclists.org/fulldisclosure/2020/Nov/22
http://seclists.org/fulldisclosure/2020/Nov/20