A validation issue was addressed with improved logic. This issue is fixed in iOS 12.2, tvOS 12.2, watchOS 5.2, Safari 12.1, iTunes 12.9.4 for Windows, iCloud for Windows 7.11. Processing maliciously crafted web content may result in the disclosure of process memory.
https://support.apple.com/HT209605
https://support.apple.com/HT209604
https://support.apple.com/HT209603
https://support.apple.com/HT209602