A memory corruption issue was addressed with improved validation. This issue is fixed in iOS 12.1.3, macOS Mojave 10.14.3, tvOS 12.1.2. A malicious application may be able to elevate privileges.
https://www.exploit-db.com/exploits/46248/
https://support.apple.com/HT209447
https://support.apple.com/HT209446