An out-of-bounds read issue existed that led to the disclosure of kernel memory. This was addressed with improved input validation. This issue is fixed in iOS 12.1.3, macOS Mojave 10.14.3, tvOS 12.1.2, watchOS 5.1.3. A malicious application may be able to determine kernel memory layout.
https://www.exploit-db.com/exploits/46285/
https://support.apple.com/HT209448
https://support.apple.com/HT209447
https://support.apple.com/HT209446