MS13-094: Description of the security update for Outlook 2010: November 12, 2013

Applies to: Microsoft Outlook 2010


This update resolves a security vulnerability in Microsoft Outlook that could allow information disclosure when a specially crafted email message is opened or previewed.


Microsoft has released security bulletin MS13-094. To view the complete security bulletin, go to one of the following Microsoft websites:

How to obtain help and support for this security update

Help installing updates: Support for Microsoft Update

Security solutions for IT professionals: TechNet Security Troubleshooting and Support

Help protect your computer that is running Windows from viruses and malware: Virus Solution and Security Center

Local support according to your country: International Support

More information about this security update

Download information

This update is available for download from the Microsoft Download Center:

Known issues with this security update

After this update is applied, you may experience issues with S/MIME certificate verification in Microsoft Outlook. This issue is caused because the update disables remote intermediate certificate fetching in Outlook.

If you experience these issues or if you are working in an enterprise installation that requires the retrieval of remote certificates referenced in an authority information access extension, a registry key can be set to enable remote intermediate certificate fetching in Microsoft Outlook.

Warning Setting the registry key to enable remote intermediate certificate fetching will remove the protections provided by this update.

Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

To enable remote intermediate certificate fetching in Outlook after this update is applied, set the following registry key value:

Registry location: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\14.0\Outlook\Security

DWORD name: EnableAIACertExtension
Value data: 1

  • You may have to create the Security subkey and the EnableAIACertExtension DWORD entry if they do not exist.
  • To disable the evaluation, set the Value data to 0 (0 is the default).

Additionally, you can apply this registry key change across domains by using Group Policy. For more information about Group Policy, see the TechNet article, Group Policy collection.

Prerequisites to apply this security update

To apply this security update, you must have Service Pack 1 or Service Pack 2 for Microsoft Office 2010 installed on the computer.

Restart information

You may have to restart the computer after you install this security update.

In some cases, this update does not require a restart. If the required files are being used, this update will require a restart. If this behavior occurs, a message is displayed that advises you to restart the computer.

To help reduce the possibility that a restart will be required, stop all affected services and close all applications that may use the affected files before you install this security update.

See Why you may be prompted to restart your computer after you install a security update on a Windows-based computer for more information.

Removal information

Note We do not recommend that you remove any security update.

To remove this security update, use the Add or Remove Programs item or use the Programs and Features item in Control Panel.

Note When you remove this security update, you may be prompted to insert the disc that contains Microsoft Office. Additionally, you may not have the option to uninstall this security update from the Add or Remove Programs item or the Programs and Features item in Control Panel. There are several possible causes for this issue.

See Information about the ability to uninstall Office updates for more information.

Security update replacement information

This security update replaces security update 2794707 .