Safari Content-Disposition Handling Could Allow Cross-site Scripting

Executive Summary

Microsoft is providing notification of the discovery and remediation of a vulnerability affecting Apple Safari software version 5.1.5 (7534.55.3) for Windows and earlier. Microsoft discovered and disclosed the vulnerability under coordinated vulnerability disclosure to the affected vendor, Apple. Apple has remediated the vulnerability in their software.

The vulnerability exists in the way that Apple Safari handles files with the content disposition header set to ‘attachment’. When a file with this value set is opened within the browser any script within the file could be executed inline.

Microsoft Vulnerability Research reported this issue to and coordinated with Apple to ensure remediation of this issue. The vulnerability has been assigned the entry, CVE-2011-3426, in the Common Vulnerabilities and Exposures list. For more information, including information about updates from Apple, see Apple security updates.

Mitigating Factors

• An attacker must convince a victim to click a specially crafted URL or to access a file on a website through Safari, for example by opening an attachment in a web-based email application.