Description of the Security Only update for the .NET Framework 3.5 for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2: September 12, 2017


Summary


This security update resolves a vulnerability in the Microsoft .NET Framework that could allow remote code execution when Microsoft .NET Framework processes untrusted input. An attacker who successfully exploits this vulnerability in software by using the .NET Framework could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts that have full user rights. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate by using administrative user rights.

To exploit the vulnerability, an attacker must first convince the user to open a malicious document or application.

This security update addresses the vulnerability by correcting how the .NET Framework validates untrusted input. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2017-8759.

Important

  • All updates for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 require update 2919355 to be installed. We recommend that you install update 2919355 on your Windows RT 8.1-based, Windows 8.1-based, or Windows Server 2012 R2-based computer so that you receive updates in the future.
  • If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.

Additional information about this security update


For more information about this security update as it relates to Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2, see the following article in the Microsoft Knowledge Base:

4041092 Security Only update for the .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2 and 4.7 updates for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2: September 12, 2017

How to obtain and install the update


Method 1: Microsoft Update Catalog

To get the stand-alone package for this update, go to the Microsoft Update Catalog.
 

Method 2: Windows Software Update Services (WSUS)

On your WSUS server, follow these steps:

  1. Click Start, click Administrative Tools, and then click Microsoft Windows Server Update Services 3.0.
  2. Expand ComputerName, and then click Action.
  3. Click Import Updates.
  4. WSUS opens a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.
  5. After the control is installed, you see the Microsoft Update Catalog screen. Enter 4041092 into the Search box, and then click Search.
  6. Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Click Add to add them to your basket.
  7. After you select all the packages that you need, click View Basket.
  8. Click Import to import the packages to your WSUS server.
  9. To return to WSUS, click Close after the packages have been imported.

The updates are now available for installation through WSUS.

Update deployment information

For deployment details for this security update, go to the following article in the Microsoft Knowledge Base:

20170912 Security update deployment information: September 12, 2017

Update removal information

Note We do not recommend that you remove any security update. To remove this update, use the Programs and Features item in Control Panel.

Update restart information

This update does not require a system restart after you apply it unless files that are being updated are locked or are being used.

Update replacement information

This update replaces update 2978122.

File information


 

How to obtain help and support for this security update


Applies to


This article applies to the following:

 

  • Microsoft .NET Framework 3.5 when used with:
    • Windows Server 2012 R2
    • Windows RT 8.1
    • Windows 8.1