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Adobe Reader and Acrobat JpxDecode Memory Corruption Vulnerability



Adobe Reader and Acrobat are Portable Document Format (PDF) reader and processors. For more information, please visit following pages:


Remote exploitation of a memory corruption vulnerability in multiple versions of Adobe Systems Inc.'s Reader and Acrobat PDF reader and processor could allow an attacker to execute arbitrary code with the privileges of the current user.

The vulnerability occurs when processing the Jp2c stream of a JpxDecode encoded data stream within a PDF file. During the processing of a JPC_MS_RGN marker, an integer sign extension may cause a bounds check to be bypassed. This results in an exploitable memory corruption vulnerability.


Exploitation of this vulnerability allows an attacker to execute arbitrary code with the privileges of the user opening the file. The attacker will have to create a malicious PDF file and convince the victim to open it. This can be accomplished by embedding the PDF file into an IFrame inside of a Web page, which will result in automatic exploitation once the page is viewed. The file could also be e-mailed as an attachment or placed on a file share. In these cases, a user would have to manually open the file to trigger exploitation. If preview is enabled in Windows Explorer, Acrobat will try to generate a preview for PDF files when a folder containing PDF files is accessed, thus triggering the exploitation.


iDefense has confirmed the existence of this vulnerability in latest version of Adobe Reader, at the time of testing, version 9.1.0. Previous versions may also be affected.

Adobe has stated that all 9.2 and below versions, as well as all 8.1.7 and below versions are vulnerable.


None of the following workarounds will prevent exploitation, but they can reduce potential attack vectors and make exploitation more difficult.

Prevent PDF documents from being opened automatically by the Web browser
Disable JavaScript
Disable PDFShell extension by removing or renaming the Acrord32info.exe file


Adobe has released a patch which addresses this issue. Information about downloadable vendor updates can be found by clicking on the URLs shown.


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2009-3955 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


08/06/2009 Initial Contact
08/06/2009 Initial Response
09/16/2009 Vendor requested POC. iDefense sent POC.
09/17/2009 Vendor response.
01/12/2010 Coordinated public disclosure.


This vulnerability was reported to iDefense by Code Audit Labs

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Copyright © 2010 Verisign, Inc.

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