TippingPoint Zero Day Initiative

(Pwn2Own) Apple OS X WindowServer Use-After-Free Privilege Escalation Vulnerability

ZDI-16-358: May 26th, 2016


CVSS Score

Affected Vendors

Affected Products

Vulnerability Details

This vulnerability allows local attackers to execute arbitrary code on vulnerable installations of Apple OS X. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the handling of CFData objects within the WindowServer process. An attacker can cause a CFData object in memory to be reused after it has been freed. An attacker can leverage this vulnerability to execute arbitrary code under the context of the WindowServer.

Vendor Response

Apple has issued an update to correct this vulnerability. More details can be found at:

Disclosure Timeline

    2016-03-16 - Vulnerability reported to vendor
    2016-05-26 - Coordinated public release of advisory


This vulnerability was discovered by:
    Liang Chen
    Yubin Fu
    Marco Grassi of KeenLab