April 13, 2021—KB5001347 (OS Build 14393.4350) - EXPIRED

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 = “  ” (string with one empty space)

  • svcKBNumber = “  ” (string with one empty space)

  • svcUpdateVersion = 11.0.1000.

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

• Address an issue that causes a system to stop working occasionally when users sign out or disconnect from remote sessions.

• Addresses an issue with a heap leak that might cause explorer.exe to consume high amounts of memory.

• 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 a race condition that causes PowerShell to stop working periodically and generates an Access Violation error. This issue occurs when you enable transcription on the system and run multiple PowerShell scripts simultaneously.

• Addresses an issue that causes the sleep time defined in HKLM\Software\Microsoft\AppV\MAV\Configuration\MaxAttachWaitTimeInMilliseconds to be shorter than intended.

• Addresses an issue in which a principal in a trusted MIT realm fails to obtain a Kerberos service ticket from Active Directory domain controllers (DC). This occurs on devices that installed Windows Updates that contain CVE-2020-17049 protections and configured PerfromTicketSignature to 1 or higher. These updates were released between November 10, 2020 and December 8, 2020. Ticket acquisition also fails with the error, “KRB_GENERIC_ERROR”, if callers submit a PAC-less Ticket Granting Ticket (TGT) as an evidence ticket without providing the USER_NO_AUTH_DATA_REQUIRED flag.

• Addresses an issue with high memory usage when performing XSLT transforms using MSXLM6.

• Addresses an issue in spaceport.sys that might cause stop error 0x7E.

• Addresses an issue with evaluating the compatibility status of the Windows ecosystem to help ensure application and device compatibility for all updates to Windows.

• 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 Windows Apps, Windows Input and Composition, Windows Office Media, Windows Fundamentals, Windows AI Platform, Windows Hybrid Cloud Networking, the 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