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Multiple COM objects cause memory corruption in Microsoft Internet Explorer

Vulnerability Note VU#959049

Original Release Date: 2005-08-09 | Last Revised: 2006-08-09


Microsoft Internet Explorer (IE) allows instantiation of COM objects not designed for use in the browser, which may allow a remote attacker to execute arbitrary code or crash IE.


Microsoft COM

Microsoft COM is a technology that allows programmers to create reusable software components that can be incorporated into applications to extend their functionality. Microsoft COM includes COM+, Distributed COM (DCOM), and ActiveX Controls.

ActiveX controls

ActiveX controls are COM objects that have visual elements. ActiveX controls are traditionally designed to be used in Internet Explorer. A web page can make use of an ActiveX control in various ways, such as by referencing its Class Identifier (CLSID) in an HTML OBJECT tag.

The Problem

Internet Explorer will attempt to instantiate any COM object that is referenced by a web page. Certain COM objects that are not designed for use in Internet Explorer may cause unexpected results, such as executing arbitrary code or crashing the browser.

Exploit code for these vulnerabilities are publicly available.


By convincing a user to view a specially crafted HTML document (e.g., a web page, an HTML email message, or an email attachment), an attacker could execute arbitrary code with the privileges of the user. The attacker could also cause IE (or the program using the WebBrowser control) to crash.


Apply An Update
Apply the appropriate update, as specified in Microsoft Security Bulletin MS06-042. This update sets the "kill bit" for certain CLSID values of COM objects known to be vulnerable. The MS06-042 update is similar to MS06-021, MS06-013, MS05-054, MS05-037, MS05-038, and MS05-052, but it includes additional COM objects.

Microsoft has listed several workarounds in the Microsoft Security Bulletin, including disabling ActiveX controls.

Vendor Information


Microsoft Corporation Affected

Notified:  September 01, 2005 Updated: August 08, 2006



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 se Microsoft Security Bulletin MS06-042.

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.

Other Information

CVE IDs: CVE-2005-1990
Severity Metric: 45.56
Date Public: 2005-08-09
Date First Published: 2005-08-09
Date Last Updated: 2006-08-09 22:06 UTC
Document Revision: 38

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