April 13, 2021—KB5001339 (OS Build 17134.2145

Highlights

• Updates to improve security when Windows performs basic operations.

• Updates to improve security when using input devices such as a mouse, keyboard, or pen.

Improvements and fixes

This security update includes quality improvements. Key changes include:

• Updates the default values for the following Internet Explorer registry keys:

  • svcKBFWLink = “” (empty string)

  • svcKBNumber = “” (empty string)

  • svcUpdateVersion = 11.0.1000.

    In addition, these values will no longer be updated automatically. 

• Updates the Volgograd, Russia time zone from UTC+4 to UTC+3.

• Adds a new time zone, UTC+2:00 Juba, for the Republic of South Sudan.

• Addresses an issue with security vulnerabilities identified by a security researcher. Because of these security vulnerabilities, this and all future Windows updates will no longer contain the RemoteFX vGPU feature. For more information about the vulnerability and its removal, see CVE-2020-1036 and KB4570006. Secure vGPU alternatives are available using Discrete Device Assignment (DDA) in Windows Server LTSC releases (Windows Server 2016 and Windows Server 2019) and Windows Server SAC releases (Windows Server, version 1803 and later versions).

• Addresses an issue that prevents you from specifying up to 255 columns when you use the Jet Text installable indexed sequential access method (IISAM) format.

• Addresses an issue that causes Windows Back up using File History to stop working for a few users. This issue occurs after installing the February 9, 2021 update. The error message is, “Failed to start the backup of user links (error 8007005)”.

• Security updates to the Windows App Platform and Frameworks, Windows Apps, Windows Input and Composition, Windows Office Media, Windows Fundamentals, Windows Cryptography, the Windows AI Platform, Windows Hybrid Cloud Networking, Windows Kernel, and Windows Media.

If you installed earlier updates, only the new fixes contained in this package will be downloaded and installed on your device.

For more information about the resolved security vulnerabilities, please refer to the new Security Update Guide website.

Known issues in this update

Microsoft is not currently aware of any issues with this update.

How to get this update

Before installing this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update, the latest SSU (KB5001400) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog. 

Install this update

File information

For a list of the files that are provided in this update, download the file information for cumulative update 5001339.