KB5013963

Updated May 27, 2022

After installing updates released May 10, 2022 on your domain controllers, you might see machine certificate authentication failures on the server or client for services such as Network Policy Server (NPS), Routing and Remote access Service (RRAS), Radius, Extensible Authentication Protocol (EAP), and Protected Extensible Authentication Protocol (PEAP). An issue has been found related to how the mapping of certificates to machine accounts is being handled by the domain controller.

Note Installation of updates released May 10, 2022, on client Windows devices and non-domain controller Windows Servers will not cause this issue. This issue only affects installation of May 10, 2022, updates installed on servers used as domain controllers.

Updated May 27, 2022

The preferred mitigation for this issue is to manually map certificates to a machine account in Active Directory. For instructions, please see Certificate Mapping.

Note The instructions are the same for mapping certificates to user or machine accounts in Active Directory. If the preferred mitigation will not work in your environment, please see KB5014754—Certificate-based authentication changes on Windows domain controllers for other possible mitigations in the SChannel registry key section.

Note Any other mitigation except the preferred mitigations might lower or disable security hardening.

This issue was addressed in out-of-band updates released May 19, 2022 for installation on all Domain Controllers in your environment, as well as all intermediary application servers such as Network Policy Servers (NPS), RADIUS, Certification Authority (CA), or web servers which passes the authentication certificate from the client being authenticated to the authenticating DC. If you used any workaround or mitigations for this issue, they are no longer needed, and we recommend you remove them. This includes the removal of the registry key (CertificateMappingMethods = 0x1F) documented in the SChannel registry key section of KB5014754. There is no action needed on the client side to resolve this authentication issue.

To get the standalone package for these out-of-band updates, search for the KB number in the Microsoft Update Catalog. You can manually import these updates into Windows Server Update Services (WSUS) and Microsoft Endpoint Configuration Manager. For WSUS instructions, see WSUS and the Catalog Site. For Configuration Manger instructions, see Import updates from the Microsoft Update Catalog. Note The below updates are not available from Windows Update and will not install automatically.

Cumulative updates:

• Windows Server 2022: KB5015013

• Windows Server, version 20H2: KB5015020

• Windows Server 2019: KB5015018

• Windows Server 2016: KB5015019

Note You do not need to apply any previous update before installing these cumulative updates. If you have already installed updates released May 10, 2022, you do not need to uninstall the affected updates before installing any later updates including the updates listed above.