The HTTP referrer header may be used to leak browsing history. The issue was resolved by downgrading all third party referrers to their origin. This issue is fixed in Safari 13.0.3, iTunes 12.10.2 for Windows, iCloud for Windows 10.9.2, tvOS 13.2, iOS 13.2 and iPadOS 13.2, iCloud for Windows 7.15. Visiting a maliciously crafted website may reveal the sites a user has visited.
https://support.apple.com/en-us/HT210947
https://support.apple.com/en-us/HT210728
https://support.apple.com/en-us/HT210726
https://support.apple.com/en-us/HT210725