A buffer overflow was addressed with improved bounds checking. This issue is fixed in iOS 12.2, macOS Mojave 10.14.4, tvOS 12.2, watchOS 5.2, iTunes 12.9.4 for Windows, iCloud for Windows 7.11. A malicious application may be able to elevate privileges.
https://support.apple.com/HT209605
https://support.apple.com/HT209604
https://support.apple.com/HT209602
https://support.apple.com/HT209601