Vulnerability Note VU#889484

libpng off-by-one vulnerability

Overview

A vulnerability exists in libpng that may allow a remote attacker to cause a denial of service.

I. Description

A vulnerability in the way libpng handles files that contain multiple zTXt chunks may cause a denial of service. This vulnerability is due to an off-by-one error introduced in the png_push_read_zTXt() function in libpng-1.2.30/pngpread.c. According to the PNG Development Group:

Gecko-based applications such as Firefox are not vulnerable because they contain a png_set_keep_unknown_chunks() call that causes the application to ignore the zTXt chunk.

Note that this issue affects libpng versions 1.0.38, 1.0.39, 1.2.30, 1.2.31, and libpng-1.4.0beta.

II. Impact

A remote, unauthorized attacker may be able to cause a denial of service.

III. Solution

Upgrade

The PNG Development Group has issued an upgrade to address this issue. See libpng version 1.2.32 for more information.

Systems Affected

Vendor	Status	Date Notified	Date Updated
libpng	Vulnerable		2008-10-02

References

http://sourceforge.net/tracker/index.php?func=detail&aid=2095669&group_id=5624&atid=105624
http://sourceforge.net/mailarchive/forum.php?thread_name=e56ccc8f0809180317u6a5306fg14683947affb3e1b%40mail.gmail.com&forum_name=png-mng-implement

Credit

This issue was reported by the PNG Development Group in libpng version 1.2.32.

This document was written by Chris Taschner.

Other Information

Date Public:	2008-09-05
Date First Published:	2008-10-02
Date Last Updated:	2008-10-02
CERT Advisory:
CVE-ID(s):	CVE-2008-3964
NVD-ID(s):	CVE-2008-3964
US-CERT Technical Alerts:
Metric:	3.97
Document Revision:	7

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Produced 2008 by US-CERT, a government organization
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