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Oracle Java Runtime Environment t2k.dll TrueType Font Parsing Memory Corruption Vulnerability



Oracle's JRE is a platform that supports the execution of programs developed using the Java programming language. It is available for multiple platforms, including Windows, Linux and MacOS. The JRE platform also supports Java Applets, which can be loaded from Web pages.


Remote exploitation of a memory corruption vulnerability in Oracle Corp.'s Java Runtime Environment (JRE) could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability exists within the font parsing code in the JRE. As part of its font API, the JRE provides the ability to load a font from a remote URL. Various types of fonts are supported, one of which is the TrueType font format. The vulnerability occurs when parsing various structures in TrueType font files. During parsing, JRE fails to properly initialize a funtion pointer. Since the funtion pointer is uninitialized, it contains random contents that are remaining from prior use. When the function pointer is later accessed, this random memory is used to make a function call. This may result in the execution of arbitrary code.


Exploitation of this vulnerability results in the execution of arbitrary code with the privileges of the current user. In order to exploit this vulnerability, a user must load a Web page containing a specially crafted Java applet. An attacker typically accomplishes this via social engineering or injecting content into compromised, trusted sites. Typical social engineering attacks will pass URLs as part of instant messages or e-mail.

To exploit this vulnerability, an attacker needs to be able to control the area of memory that is unintialized and used as the function pointer. An attacker has several methods of doing this via reallocating it or by heap spraying.


The following Java versions are vulnerable:

  • Sun Java Version 7 Update 7 and before (P-856V-7 Update 7 and before)
  • Sun Java Version 6 Update 35 and before (P-856V-6 Update 35 and before)
  • Sun Java Version 5.0 Update 36 and before (P-856V-5.0 Update 36 and before)
  • Sun Java Version 1.4.2_38 and before (P-856V-1.4.2_38 and before)
  • Sun Java Version JavaFX 2.2 and before (P-856V-JavaFX 2.2 and before)


It is possible to disable the Java plug-in in Internet Explorer, Firefox, Safari, Opera and Google Chrome.


Oracle Corp. has released an update 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-2012-1531 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


06/20/2012 Initial Vendor Notification
06/20/2012 Initial Vendor Reply
10/16/2012 Coordinated Public Disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2012 Verisign, Inc.

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