Applies ToWindows 10, version 1809, all editions Windows Server version 1809 Windows Server 2019, all editions

Release Date:

4/13/2021

Version:

OS Build 17763.1879

NEW 4/13/21 IMPORTANT Windows 10, version 1809 will reach end of service on May 11, 2021 for devices running the Enterprise, Education, and IoT Enterprise editions. After May 11, 2021, these devices will no longer receive monthly security and quality updates that contain protection from the latest security threats. To continue receiving security and quality updates, Microsoft recommends updating to the latest version of Windows 10.

We will continue to service the following editions: Enterprise G, HoloLens, and the LTSC editions for Client, Server, and IoT.

2/16/21 IMPORTANT As part of the end of support for Adobe Flash, KB4577586 is now available as an optional update from Windows Update (WU) and Windows Server Update Services (WSUS). Installing KB4577586 will remove Adobe Flash Player permanently from your Windows device. Once installed, you cannot uninstall KB4577586. For more details about Microsoft’s plans, see Update on Adobe Flash Player End of Support.

11/17/20 For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. To view other notes and messages, see the Windows 10, version 1809 update history home page.

Note This release also contains updates for Microsoft HoloLens (OS Build 17763.1879) released April 13, 2021. Microsoft will release an update directly to the Windows Update Client to improve Windows Update reliability on Microsoft HoloLens that have not updated to this most recent OS Build.

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

  • 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 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 a potential elevation of privilege vulnerability in the way Azure Active Directory web sign-in allows arbitrary browsing from the third-party endpoints used for federated authentication. For more information, see CVE-2021-27092 and Policy CSP - Authentication.

  • 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 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, the Windows Kernel, Windows Virtualization, 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.

Windows Update Improvements

Microsoft has released an update directly to the Windows Update client to improve reliability. Any device running Windows 10 configured to receive updates automatically from Windows Update, including Enterprise and Pro editions, will be offered the latest Windows 10 feature update based on device compatibility and Windows Update for Business deferral policy. This doesn't apply to long-term servicing editions.

Known issues in this update

Symptom

Workaround

After installing KB4493509, devices with some Asian language packs installed may receive the error, "0x800f0982 - PSFX_E_MATCHING_COMPONENT_NOT_FOUND."

  1. Uninstall and reinstall any recently added language packs. For instructions, see Manage the input and display language settings in Windows 10.

  2. Select Check for Updates and install the April 2019 Cumulative Update. For instructions, see Update Windows 10.

Note If reinstalling the language pack does not mitigate the issue, reset your PC as follows:

  1. Go to the Settings app > Recovery.

  2. Select Get Started under the Reset this PC recovery option.

  3. Select Keep my Files.

Microsoft is working on a resolution and will provide an update in an upcoming release.

After installing this update, the Cluster Service might fail to start because a Cluster Network Driver is not found.

This issue occurs because of an update to the PnP class drivers used by this service.  After about 20 minutes, you should be able to restart your device and not encounter this issue. For more information about the specific errors, cause, and workaround for this issue, please see KB5003571.

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 (KB5001404) 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

Release Channel

Available

Next Step

Windows Update and Microsoft Update

Yes

None. This update will be downloaded and installed automatically from Windows Update.

Microsoft Update Catalog

Yes

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Windows Server Update Services (WSUS)

Yes

This update will automatically sync with WSUS if you configure Products and Classifications as follows:

Product: Windows 10

Classification: Security Updates

File information

For a list of the files that are provided in this update, download the file information for cumulative update 5001342.

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