An issue was discovered in certain Apple products. iOS before 10.2 is affected. macOS before 10.12.2 is affected. watchOS before 3.1.3 is affected. The issue involves the "Security" component, which allows remote attackers to spoof certificates via unspecified vectors.
https://support.apple.com/HT207487
https://support.apple.com/HT207423
https://support.apple.com/HT207422