CVE-2016-4749

Vulnerability

Printing UIKit in Apple iOS prior to 10 mishandles environment variables, resulting in the creation of a temporary file that contains cleartext AirPrint preview content. This issue affects all devices running iOS versions before 10, including iPhone 5 and later, iPad 4th generation and later, and iPod touch 6th generation and later [1]. The vulnerability is triggered when a user prints a document using AirPrint and the preview is generated.

Exploitation

An attacker must have local access to the device (e.g., as a user with physical or remote shell access). No special privileges or authentication beyond being a local user are required. The attacker can read the temporary file created during the AirPrint preview process, which is stored in an insecure location due to the environment variable mishandling. The exact file path is not publicly disclosed, but the attacker can locate it by monitoring file system activity or searching for common patterns.

Impact

Successful exploitation results in the disclosure of cleartext AirPrint preview content, which may contain sensitive information from printed documents. The impact is limited to information disclosure (confidentiality breach) and does not affect integrity or availability. The attacker gains no additional privileges beyond their existing local user access.

Mitigation

Apple addressed this vulnerability in iOS 10, released on September 13, 2016 [1]. Users should update their devices to iOS 10 or later to mitigate the issue. No workarounds are available for earlier versions. The vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.