Cumulative updates for Windows 10, April 13, 2021

Today's Patch Tuesday brought a number of cumulative updates to Windows 10 version 20H2 and older. Here's what's new in the released patches.

KB5001330 (OS Builds 19041.928 and 19042.928)

If you are running Windows 10, version 20H2, or version 2004, the patch KB5001330 will bring the following changes to the OS.

• 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.
• 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 Kernel, Windows Virtualization, and Windows Media.

KB5001337 (OS Build 18363.1500)

The update KB5001337 is available for Windows 10 version 1909, it shares the above changelog.

• 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.
• 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.

Other updates

The following updates are available for older Windows 10 releases in Enterprise channels.

• KB5001342, build 17763.1879 for Windows 10 version 1809
• KB5001339, build 17134.2145 for Windows 10 version 1803
• KB5001347, build 14393.4350 for Windows 10 version 1607
• KB5001340, build 10240.18906 for the initial Windows 10 version.

How to install the updates

To download these updates, open Settings - > Update & recovery and click on the Check for Updates button on the right.

Alternatively, you can get it from the Windows Update online catalog.

Helpful links

• Find Which Windows 10 Edition You Have Installed
• How to find the Windows 10 version you are running
• How to find the Windows 10 build number you are running
• How to install CAB and MSU updates in Windows 10

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