iDEFENSE Security Advisory 11.15.05: Multiple Vendor GTK+ gdk-pixbuf XPM Loader Heap Overflow Vulnerability
Date: 11/15/05

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    Date: Tue, 15 Nov 2005 17:49:01 -0500

    Multiple Vendor GTK+ gdk-pixbuf XPM Loader Heap Overflow Vulnerability

    iDEFENSE Security Advisory 11.15.05
    November 15, 2005


    GTK+ is a multi-platform toolkit for creating graphical user interfaces.
    Offering a complete set of widgets, GTK+ is suitable for projects
    ranging from small one-off projects to complete application suites.


    Remote exploitation of heap overflow vulnerability in various vendors'
    implementations of the GTK+ gdk-pixbuf XPM image rendering library could
    allow for arbitrary code execution.

    The vulnerability specifically exists due to an integer overflow while
    processing XPM files. The following code snippet illustrates the

    if (n_col <= 0 || n_col >= G_MAXINT / (cpp + 1)) {
                    g_set_error (error,
                                 _("XPM file has invalid number of colors"));
            return NULL;
    colors = (XPMColor *) g_try_malloc ((sizeof (XPMColor) * n_col));

    The validity check of n_col is enough to prevent an integer overflow in
    the first g_try_malloc, however there is not a proper check for the
    second g_try_malloc, which allows an undersized heap buffer to be
    allocated, then overflowed while using n_col as an upper bounds in a
    copying loop. This can be used to execute arbitrary code via traditional
    heap overflow 4 byte write methods or by overwriting adjacent areas of
    the heap with important values such as function pointers.


    Exploitation could allow for arbitrary code execution in the context of
    the user running the affected application. As this library is used in a
    variety of applications, this vulnerability could be exploited either
    remotely, via a networked application or locally.


    iDEFENSE has confirmed the existence of this vulnerability in gtk+ 2.4.0
    compiled from source. It is suspected that previous versions are also
    affected by this vulnerability. The following vendors include
    susceptible GTK+ and GdkPixBuf packages within their respective
    operating system distributions:

        The Debian Project:
          Debian GNU/Linux 3.0 and 3.1 (all architectures)
        Mandriva (formerly Mandrakesoft):
          Mandriva Linux (formerly Mandrakelinux) 10.0 and 10.1,
          Corporate Server 3.0
        Novell Inc.:
          SuSE Linux 8.2, 9.0, 9.1 and 9.2
        Red Hat Inc.:
          Red Hat Enterprise Linux 2.1, 3, 4,
          Fedora Core 3, 4


    Users should not open untrusted media files.


    Red Hat Inc.:

    "This issue affects the gtk2 packages as shipped with Red Hat Enterprise
    Linux 3 and 4, and the gdk-pixbuf packages as shipped with Red Hat
    Enterprise Linux 2.1, 3, and 4. Updates to these packages are available
    at the URL below or by using the Red Hat Network up2date tool.

    This issue affects the gtk2 and gdk-pixbuf packages as shipped with
    Fedora Core 3 and 4."


    The Common Vulnerabilities and Exposures (CVE) project has assigned the
    name CAN-2005-3186 to this issue. This is a candidate for inclusion in
    the CVE list (, which standardizes names for
    security problems.


    10/12/2005 Initial vendor notification
    10/14/2005 Initial vendor response
    11/15/2005 Coordinated public disclosure


    infamous41md is credited with the discovery of this vulnerability.

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    Copyright 2005 iDEFENSE, Inc.

    Permission is granted for the redistribution of this alert
    electronically. It may not be edited in any way without the express
    written consent of iDEFENSE. If you wish to reprint the whole or any
    part of this alert in any other medium other than electronically, please
    email for permission.

    Disclaimer: The information in the advisory is believed to be accurate
    at the time of publishing based on currently available information. Use
    of the information constitutes acceptance for use in an AS IS condition.
    There are no warranties with regard to this information. Neither the
    author nor the publisher accepts any liability for any direct, indirect,
    or consequential loss or damage arising from use of, or reliance on,
    this information.

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