Public Vulnerability Reports

Multiple Vendor WebKit Error Handling Use After Free Vulnerability



WebKit is an open source web browser engine. It is currently used by the Apple Inc.'s Safari browser, as well as by Google's Chrome browser. For more information, see the vendor's site at the following link.


Remote exploitation of a memory corruption vulnerability in multiple vendors' WebKit browser engine could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability occurs when JavaScript code is used to set a certain property of an HTML tag within a web page. When JavaScript code sets this property, child elements of the tag are freed. However, when an error in the remaining HTML is encountered, these previously freed tag values are referenced. The freed memory is then treated as a C++ object, which can lead to attacker controlled values being used as function pointers.


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.

WebKit is used by multiple applications, including Google Chrome and Apple Safari (including Safari on the iPhone). Affected versions are listed in the Detection field of this report.


iDefense has confirmed the existence of this vulnerability in WebKit-r42162. Previous versions may also be affected. Additionally, the following applications that use WebKit have been determined to be vulnerable:

 Google Chrome Safari 3.2.1 (5525.27.1) Safari 3.1.1 running on iPhone 2.2.1 (5525.27.1) 


Disabling JavaScript will prevent exploitation of this vulnerability.


Apple Inc. has released a patch 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-2009-1690 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


04/13/2009 - Initial Contact
04/14/2009 - Initial response
04/22/2009 - PoC Requested
04/23/2009 - PoC Sent
05/18/2009 - Apple inquiry about Safari 4
05/21/2009 - Responded to Apple inquiry
06/08/2009 - Coordinated public disclosure


This vulnerability was reported to iDefense by wushi&ling of team509.

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