Public Vulnerability Reports

Multiple Vendor wget/curl NTLM Username Buffer Overflow Vulnerability



GNU Wget is a free software package for retrieving files using HTTP,
HTTPS and FTP, the most widely-used Internet protocols. It is a
non-interactive commandline tool, so it may easily be called from
scripts, cron jobs, terminals without X-Windows support, etc. More
information on Wget is available from the vendor website:

curl is a command line tool for transferring files with URL syntax,
Curl supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading,
HTTP form based upload, proxies, cookies, user+password authentication
(Basic, Digest, NTLM, Negotiate, kerberos...), file transfer resume,
proxy tunneling and a busload of other useful tricks. More information
on curl is available from the vendor website:


Remote exploitation of a buffer overflow vulnerability in multiple
vendor's implementations of curl and wget allows attackers to execute
arbitrary code.

The vulnerability specifically exists due to insufficient bounds
checking on user-supplied data supplied to a memory copy operation. The
memcpy() of the supplied ntlm username to ntlmbuf shown below results
in a stack overflow:

http-ntlm.c in ntlm_output() on line 532:

    /* size is now 64 */

    memcpy(&ntlmbuf[size], domain, domlen);
    size += domlen;

    memcpy(&ntlmbuf[size], usr, userlen);
    size += userlen;

The resulting stack overflow can be leveraged to gain arbitrary code
execution with user privileges.


Successful exploitation of the vulnerability allows remote attackers to
execute arbitrary code with permissions of the http client process.
User interaction is required. Exploitation requires a user to use one
of the affected clients to connect to a malicious website.

This vulnerability affects both wget and curl clients similarly because
wget 1.10 adopted the curl ntlm authentication source code into its own
code base. The described vulnerability requires that ntlm authentication
is enabled in the affected client versions. A factor that somewhat
increases the risk of this vulnerability is that a client can be forced
to reconnect using ntlm authentication by issuing a HTTP 302 REDIRECT
command to the connecting client.


iDEFENSE Labs has confirmed the following software versions are

       wget 1.10
       curl 7.13.2
       libcurl 7.13.2


As a workaround solution, disable NTLM support in wget and curl


wget 1.10.2 has been released to address this issue and is available for
download at:

curl has released the following patch to address this issue:

curl has also released the following security advisory:
Additionally, the maintainers of curl-web have provided the following
details on affected versions:

Affected versions: curl and libcurl 7.10.6 to and including 7.14.1

Not affected versions: curl and libcurl 7.10.5 and earlier,
  7.15.0 and later


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-3185 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
10/12/2005   Initial vendor response
10/13/2005   Coordinated public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2005 Verisign, Inc.

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