CVE-2016-4643

Vulnerability

A validation issue existed in the parsing of 407 responses across multiple Apple platforms. This flaw affects iOS versions before 9.3.3, tvOS before 9.2.2, and OS X El Capitan before v10.11.6 and Security Update 2016-004 [1][2][3]. The improper validation occurs when handling HTTP 407 proxy authentication responses.

Exploitation

An attacker in a privileged network position, such as a man-in-the-middle, could craft a malicious 407 response to exploit the validation issue. The attacker would need to intercept network traffic between the device and a legitimate server. No user interaction is required beyond the device automatically handling the proxy authentication challenge.

Impact

Successful exploitation may allow an attacker to leak sensitive user information, such as authentication credentials or other data transmitted over HTTP. The impact is primarily related to information disclosure.

Mitigation

Apple addressed this issue with improved response validation. The fix is included in iOS 9.3.3 [2], tvOS 9.2.2 [3], and OS X El Capitan v10.11.6 and Security Update 2016-004 [1], all released on July 18, 2016. Users should update their devices to the latest available versions.