An out-of-bounds read was addressed with improved bounds checking. 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 read restricted memory.
https://support.apple.com/HT209448
https://support.apple.com/HT209447
https://support.apple.com/HT209446