An issue was discovered in certain Apple products. iOS before 11.4 is affected. macOS before 10.13.5 is affected. iCloud before 7.5 on Windows is affected. iTunes before 12.7.5 on Windows is affected. watchOS before 4.3.1 is affected. The issue involves the "Security" component. It allows local users to bypass intended restrictions on Keychain state modifications.
https://support.apple.com/HT208853
https://support.apple.com/HT208852
https://support.apple.com/HT208851
https://support.apple.com/HT208849
https://support.apple.com/HT208848