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libpng off-by-one vulnerability

Vulnerability Note VU#889484

Original Release Date: 2008-10-02 | Last Revised: 2008-10-02


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


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.


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


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

Vendor Information


libpng Affected

Updated:  October 02, 2008



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


See libpng version 1.2.32 for more information.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group Score Vector
Base 0 AV:--/AC:--/Au:--/C:--/I:--/A:--
Temporal 0 E:ND/RL:ND/RC:ND
Environmental 0 CDP:ND/TD:ND/CR:ND/IR:ND/AR:ND



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

This document was written by Chris Taschner.

Other Information

CVE IDs: CVE-2008-3964
Severity Metric: 3.97
Date Public: 2008-09-05
Date First Published: 2008-10-02
Date Last Updated: 2008-10-02 19:57 UTC
Document Revision: 9

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