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Notice

May 30, 2017

If you install the .NET Framework Security and Quality rollups for May 2017, and then you use a compliance scanner, such as the Microsoft Baseline Security Analyzer (MBSA), to determine the security state of the system, the .NET Framework Security Only updates for May 2017 may be flagged as missing.

To resolve this issue, we updated the applicability of the .NET Framework Security Only updates so that compliance checkers do not flag these updates as missing from the system.

If you have already installed the May 2017 Security and Quality rollups or Security Only updates for the .NET Framework, no additional action is necessary.

Summary

This security update for the Microsoft .NET Framework resolves a security feature bypass vulnerability in which the .NET Framework (and the .NET Core) components don't completely validate certificates. To learn more about this vulnerability, see Microsoft Common Vulnerabilities and Exposures CVE-2017-0248.

This update also contains security-enhancing fixes to the Windows Presentation Framework PackageDigitalSignatureManager component's ability to sign packages with the SHA256 hash algorithm.

Important

  • All future security and nonsecurity 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 future updates.

  • 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

The following articles contain additional information about this security update as it relates to individual product versions.
 

  • 4014587 Description of the Security Only update for the .NET Framework 4.6.2 for Windows 8.1 and Windows Server 2012 R2: May 9, 2017

  • 4014590 Description of the Security Only update for the .NET Framework 4.6 and 4.6.1 for Windows 8.1 and Windows Server 2012 R2: May 9, 2017

  • 4014595 Description of the Security Only update for the .NET Framework 4.5.2 for Windows 8.1 and Windows Server 2012 R2: May 9, 2017

  • 4014581 Description of the Security Only update for the .NET Framework 3.5 Service Pack 1 for Windows 8.1 and Windows Server 2012 R2: May 9, 2017

How to obtain help and support for this security update

Applies to

This article applies to the following:
 

  • Microsoft .NET Framework 3.5 Service Pack 1, 4.5.2, 4.6, 4.6.1, and 4.6.2 when used with:

    • Windows Server 2012 R2

    • Windows 8.1

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