search menu icon-carat-right cmu-wordmark

CERT Coordination Center

Microsoft Internet Explorer vulnerable to address bar spoofing on double byte character set systems

Vulnerability Note VU#431576

Original Release Date: 2004-10-13 | Last Revised: 2004-10-18


Microsoft Internet Explorer contains a vulnerability in how it processes URLs on Double Byte Character Set (DBCS) systems. This could allow an attacker to spoof the address of a web site.


Microsoft Internet Explorer contains a canonicalization error when it parses special characters in a URL on a DBCS system. A DBCS system represents characters with either a single byte or a double byte code. DBCS is used with some Asian versions of Microsoft Windows. Because of the error in how IE parses URLs on DBCS systems, a web site operator could make it appear that the content from his or her web site actually originated from another site.


By making a malicious web site appear to be a site that the user trusts, an attacker could convince the user to provide sensitive information.


Apply a patch

Apply the patch referenced in MS04-038.

Vendor Information


Microsoft Corporation Affected

Updated:  October 13, 2004



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.


Please see

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

CVSS Metrics

Group Score Vector



Thanks to Microsoft for reporting this vulnerability.

This document was written by Will Dormann, based on the information provided in the Microsoft Security Bulletin.

Other Information

CVE IDs: CVE-2004-0844
Severity Metric: 1.98
Date Public: 2004-10-12
Date First Published: 2004-10-13
Date Last Updated: 2004-10-18 16:39 UTC
Document Revision: 8

Sponsored by CISA.