Public Vulnerability Reports

Multiple Unix/Linux Vendor Xpdf makeFileKey2 Stack Overflow



Xpdf is an open-source viewer for PDF files. More information is
available at the following site:


Remote exploitation of a buffer overflow vulnerability in the xpdf PDF
viewer included in multiple Unix and Linux distributions could allow for
arbitrary code execution as the user viewing a PDF file.

The vulnerability specifically exists due to insufficient bounds
checking while processing a PDF file that provides malicious values in
the /Encrypt /Length tag. The offending code can be found in the
Decrypt::makeFileKey2 function in the source file xpdf/

GBool Decrypt::makeFileKey2(int encVersion, int encRevision,
                            int keyLength, GString *ownerKey,
                            GString *userKey, int permissions,
                            GString *fileID, String *userPassword,
                            Guchar *fileKey) {
      Guchar *buf;
      Guchar test[32];
      Guchar fState[256];
      Guchar tmpKey[16];
      Guchar fx, fy;
      int len, i, j;
      GBool ok;

            memcpy(test, userKey->getCString(), 32);
            for (i = 19; i >= 0; --i) {
                  for (j = 0; j < keyLength; ++j) {
[overflow]               tmpKey[j] = fileKey[j] ^ i;

In this piece of code, the keyLength value is ultimately supplied by the
PDF file. This allows an attacker to specify an arbitrarily large value
and overwrite portions of stack memory. As a consequence, arbitrary code
execution is possible.


Successful exploitation of this vulnerability leads to arbitrary code
execution as the user who opened the malicious file. An attacker would
have to convince a target to open the provided file in order to exploit
this vulnerability, thus lessening the impact.

Exploitation can be performed reliably, especially with knowledge of the
target system.


iDEFENSE has confirmed the existence of this vulnerability in version
3.00 of xpdf. It is suspected previous versions are vulnerable.

The following Linux vendors may be affected by this vulnerability:

 Novell Inc. (SUSE)
 Red Hat Inc.
 The Fedora Project
 Debian Project
 Gentoo Foundation Inc.
 The FreeBSD Project


Only open PDF files from trusted individuals.


A patch to address this issue is available at:

Updated binaries (ver. 3.00pl3) to address this issue are available at:


The Common Vulnerabilities and Exposures (CVE) project has assigned the
names CAN-2005-0064 to these issues. This is a candidate for inclusion
in the CVE list (, which standardizes names for
security problems.


01/06/2005   Initial vendor notification
01/12/2005   Initial vendor response
01/18/2005   Coordinated public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2005 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
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