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Apache mod_tcl module contains a format string error

Vulnerability Note VU#366020

Original Release Date: 2006-11-07 | Last Revised: 2006-11-07


A format string vulnerability exists in the mod_tcl Apache module. This vulnerability may allow a remote attacker to execute arbitrary code.


The Apache HTTP Server, also known as httpd, is an open-source HTTP server that runs on Microsoft Windows, Linux, Unix, and Apple OS X Operating Systems. Apache modules can be used to extend the functionality of the Apache web server. The mod_tcl module is a scripting module that allows Apache to run TCL scripts natively.

There is a format string vulnerability in the mod_tcl module that may allow an attacker to execute arbitrary code.


A remote, unauthenticated attacker may be able to execute arbitrary code with the privileges of the httpd process.


The mod_tcl team has released an upgrade that addresses this issue.

Install only required modules

Only install the modules that are necessary for the operation of the web server.

Restrict access

Restricting access to a vulnerable system to trusted hosts until an upgrade can be applied may mitigate the affects of this vulnerability.

Vendor Information

Affected   Unknown   Unaffected

Apache HTTP Server Project

Updated:  November 07, 2006



Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

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

CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A



Thanks to the mod_tcl and Gentoo teams for providing information about this vulnerability.

This document was written by Ryan Giobbi.

Other Information

CVE IDs: CVE-2006-4154
Severity Metric: 3.99
Date Public: 2006-10-14
Date First Published: 2006-11-07
Date Last Updated: 2006-11-07 18:56 UTC
Document Revision: 27

Sponsored by the Department of Homeland Security Office of Cybersecurity and Communications.