This website uses cookies to distinguish you from other users of our website. The use of cookies helps us to provide you with a specific service, to facilitate website use, to understand our visitors and to advertise to you. By continuing to browse the site you are giving consent to our use of cookies. Learn more in our Privacy Statement.

Security Services

Apple Safari font-face Use-After-Free Vulnerability



Safari is Apple's web browser, and is based on the open source WebKit browser engine. MobileSafari is Safari for Apple's mobile devices including the iPad and iPhone. For more information, see the vendor's site found at the following link.


Remote exploitation of a memory corruption vulnerability in Apple Inc.'s Safari browser could allow an attacker to execute arbitrary code with the privileges of the current user.

Safari is Apple's Web browser and is based on the open source WebKit browser engine.

This vulnerability occurs when handling font-face elements that have been improperly appended. Specifically, Safari fails to properly remove a stale reference from a list of elements. When this occurs, the object is reused after it has been freed. This results in uninitialized heap memory being treated as an object pointer, which can result in the execution of arbitrary code.


Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the user viewing the Web page. To exploit this vulnerability, a targeted user must load a malicious Web page created by an attacker. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. After the user visits the malicious Web page, no further user interaction is needed.


The following Apple products and versions are vulnerable:

  • Safari versions 5.1 and prior

    Disabling JavaScript is an effective workaround for this vulnerability.


    Apple Inc. has released patches which addresses this issue. For more information, consult their advisory at the following URL:


    The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2011-3443 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


    06/01/2011 Initial Vendor Notification
    06/01/2011 Initial Vendor Reply
    11/16/2011 Coordinated Public Disclosure


    This vulnerability was reported to iDefense by anonymous.

    Get paid for vulnerability research

    Free tools, research and upcoming events


    Copyright © 2011 Verisign, Inc.

    Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

    Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.