An issue was discovered in certain Apple products. iOS before 11.2.5 is affected. macOS before 10.13.3 is affected. tvOS before 11.2.5 is affected. watchOS before 4.2.2 is affected. The issue involves the "Security" component. It allows remote attackers to spoof certificate validation via crafted name constraints.
https://support.apple.com/HT208465
https://support.apple.com/HT208464
https://support.apple.com/HT208463
https://support.apple.com/HT208462
http://www.securitytracker.com/id/1040267