In iOS before 11.4.1, watchOS before 4.3.2, tvOS before 11.4.1, Safari before 11.1.1, macOS High Sierra before 10.13.6, a spoofing issue existed in the handling of URLs. This issue was addressed with improved input validation.
https://support.apple.com/HT208938
https://support.apple.com/HT208937
https://support.apple.com/HT208936
https://support.apple.com/HT208935