An issue was discovered in certain Apple products. iOS before 10.1 is affected. macOS before 10.12.1 is affected. tvOS before 10.0.1 is affected. The issue involves the "CFNetwork Proxies" component, which allows man-in-the-middle attackers to spoof a proxy password authentication requirement and obtain sensitive information.
https://support.apple.com/HT207275
https://support.apple.com/HT207271
https://support.apple.com/HT207270