An issue was discovered in certain Apple products. iOS before 11 is affected. macOS before 10.13 is affected. tvOS before 11 is affected. watchOS before 4 is affected. The issue involves the "Security" component. It allows remote attackers to bypass intended certificate-trust restrictions via a revoked X.509 certificate.
https://support.apple.com/HT208144
https://support.apple.com/HT208115
https://support.apple.com/HT208113
https://support.apple.com/HT208112