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 "libarchive" component, which allows local users to write to arbitrary files via vectors related to symlinks.
https://support.apple.com/HT207487
https://support.apple.com/HT207423
https://support.apple.com/HT207422