Those of you on Windows XP SP2 should not be affected, according to the patch notes. Pretty much everyone else is.
Originally posted by MicrosoftMicrosoft Security Bulletin MS04-040 Cumulative Security Update for Internet Explorer (889293)
Issued: December 1, 2004 Version: 1.0
Summary Who should read this document: Customers who use Microsoft Windows
Impact of Vulnerability: Remote Code Execution
Maximum Severity Rating: Critical
Recommendation: Customers should install the update immediately.
Security Update Replacement: This update replaces the update that is included with Microsoft Security Bulletin MS04-038. That update is also a cumulative update.
Caveats: Microsoft Knowledge Base Article 889293 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues.
Important: This update may not include hotfixes that have been released since the release of MS04-004 or MS04-038. Customers who have received hotfixes from Microsoft or from their support providers since the release of MS04-004 or MS04-038 should not install this update. Instead customers should deploy update 889669.
This update contains several functionality and security changes which are documented in the FAQ section for this update.
Tested Software and Security Update Download Locations:
• Microsoft Windows NT Server 4.0 Service Pack 6a
• Microsoft Windows NT Server 4.0 Terminal Server Edition Service Pack 6
• Microsoft Windows 2000 Service Pack 3 and Microsoft Windows 2000 Service Pack 4
• Microsoft Windows XP Service Pack 1
• Microsoft Windows XP 64-Bit Edition Service Pack 1
• Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and Microsoft Windows Millennium Edition (Me) – Review the FAQ section of this bulletin for details about these operating systems.
• Microsoft Windows XP Service Pack 2
• Microsoft Windows XP 64-Bit Edition Version 2003
I'm going to comment here so that you don't think I've missed this post I've had a hell of a time with search, and I can't recommend anything. You may want to buy the Google search appliance if they still sell it.