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Multiple Vendor WebKit JRE Plugin Module Use-after-Free Vulnerability



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


Remote exploitation of a use-after-free vulnerability in WebKit, as included with multiple vendors' browsers, could allow an attacker to execute arbitrary code with the privileges of the current user.

This vulnerability occurs due to an interaction between the JRE plug-in for WebKit-based browsers and the browser's JavaScript engine. When DOM nodes containing applet elements are manipulated via JavaScript, a reference counting error occurs. This results in the plug-in module being unloaded while a return address pointing inside of it still resides on the stack. The result is that a stale return address is used when control returns from an asynchronous JavaScript Event Handler. This can lead to 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 that an attacker has created. 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.


JRE 7 Update 11 and prior, 6 Update 38 and prior are vulnerable.


Disabling the JRE plug-in is an effective workaround for this vulnerability.


Oracle has released a fix 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-2012-1541 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


04/04/2012 Initial Vendor Notification
04/19/2012 Initial Vendor Reply
02/01/2013 Coordinated Public Disclosure


This vulnerability was reported to iDefense by wushi of team509.

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Copyright © 2013 Verisign, Inc.

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