November 10, 2026—KB5131090 (OS Build 20348.5870)

This cumulative update for Windows Server 2022 (KB5131090), includes the latest security fixes and improvements, along with non-security updates from last month’s optional preview release. Visit the Windows release health dashboard for the latest status on this release.

Announcements and messages

This section provides key notifications related to this release, including announcements, change logs, and end-of-support notices.

Windows Secure Boot certificate expiration

Important: Secure Boot certificate updates remain in progress as Microsoft transitions devices from certificates that began expiring in 2026 to newer certificates. Devices that have not yet received the newer certificates can continue to start and receive standard Windows updates. Microsoft will continue delivering the newer Secure Boot certificates to eligible devices through Windows Update.

Improvements

This security update contains fixes and quality improvements from KB5126655 (released October 13, 2026) and the out-of-band update KB5134140(released October26, 2026). The following summary outlines key issues addressed by this update. Also, included are available new features. The bold text within the brackets indicates the item or area of the change.

• [Date and Time] This update adjusts daylight saving time (DST) rules for Cuba for the extended 2026-2027 DST period. Cuba remains on UTC-04:00 and doesn't observe the November 2026 and March 2027 transitions. It returns to UTC-05:00 in November 2027 and resumes its regular seasonal schedule in 2028. For the latest DST and time zone guidance, see the Daylight Saving Time & Time Zone Blog.
• [Exchange Server] This update fixes an issue that affects on-premises Exchange servers. The issue might prevent signing in to Outlook on the web (OWA), cause email messages to remain in the Outlook Outbox without being delivered, or prevent Exchange from accessing mailboxes during mailbox replication.
• [Printing] Fixed: Adding a printer published in Active Directory through Settings > Bluetooth & devices > Printers & scanners > Add device might fail with error 87, “The parameter is incorrect.” This issue was introduced by the October 2026 update and does not generally affect existing printers or printing.
• [Remote Desktop] Fixed: The “Specify thumbprints of certificates representing trusted .rdp publishers” policy could not be configured successfully through Microsoft Intune.
• [Remote Desktop Web Access] Fixed: RD Web Access might fail to load and display “Unable to display RD Web Access” in Microsoft Edge or Google Chrome when XSLT is disabled by browser policy. RD Web Access pages are now rendered on the server and no longer depend on browser XSLT support. To learn more, see KB5130994: RD Web Access fails to load when XSLT is disabled in Microsoft Edge or Google Chrome.
• [Security] This update improves NTLM security by enabling clients to offer NTLM message signing by default for non-anonymous connections. This change helps reduce exposure to NTLM relay attacks and provides auditing to identify connections that are not using signing. To learn more, see NTLM signing security improvements in Windows.
• [Windows Deployment Services] Fixed: After installing this security update, the Import-WdsInstallImage cmdlet requires administrator privileges. Attempts to run the cmdlet as a non-administrator fail with an ACCESS_DENIED error.
• [Windows PowerShell] This update strengthens security for PowerShell script signing and signature verification by introducing stricter encoding validation. As a result, scripts containing invalid UTF-8 encoding might fail signature validation, even if they were previously accepted. To resolve this issue, review the affected scripts, save them using valid UTF-8 encoding with a byte order mark (BOM), and sign them again. For further guidance, see Encoding Guidance for Signed PowerShell Scripts.

If you've already installed previous updates, your device will download and install only the new updates included in this package.

For more information about security vulnerabilities, see the Security Update Guide and the November 2026 Security Updates.

Windows Server 2022 servicing stack update (KB5131089) - 20348.5859

This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. To learn more about SSUs, see Servicing stack updates.

Known issues in this update

Users might be unable to sign in to OWA or send emails on Exchange Server

Symptoms:

After installing this update, some on-premises Exchange servers might experience issues accessing or sending email. Users might be unable to sign in to Outlook on the web (OWA), or email messages sent from Outlook might remain in the Outbox and not be delivered. Additionally, Exchange might experience issues accessing mailboxes during mailbox replication.

In some affected configurations, Exchange Server OWA might fail with an error MapiExceptionMdbOffline: Unable to make connection to the server. (hr=0x80004005, ec=1142) with Event ID 1006 logged in the application log. Another reported symptom is growing email queues. Installing the October 2026 Exchange server security updates isn’t required for these issues to occur.

Resolution

This issue is resolved in Windows updates released on and after November 10, 2026 such as (KB5131090). We recommend you install the latest Windows update for your device as it contains important improvements and issue resolutions, including this one.

Windows Server Update Services (WSUS) does not display error details

After installing KB5070884 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287.

How to get this update

Before you install this update

• For Windows Update: You must have the Windows update released on or after July 8, 2025 (such as KB5062572) installed before installing this update.

• For Windows Server Update Services (WSUS) deployment or when installing the standalone package from Microsoft Update Catalog: You must have the Windows update released on or after July 8, 2025 (such as KB5062572) installed before installing this update.

• For offline OS image servicing: Make sure that your image includes a Windows update released on or after September 12, 2023 (such as KB5030216). If not, install it on your offline media before you install the latest update. This update installs SSU version 20348.1960. That is the minimum SSU version you must have to prevent error 0x800f0823 (CBS_E_NEW_SERVICING_STACK_REQUIRED).

• Servicing Stack Update (SSU): You must have installed servicing stack update version 20348.3920 or later before installing this update. To determine the latest SSU installed on your device, run DISM /Online /Get-Packages | findstr /i "ServicingStack" from an elevated command prompt. The Package Identity line returned must be version 20348.3920 or later.

Deployment

If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.

To ensure the boot.stl file is included as part of the installation media, do one of the following:

• Use the Update WinPE script to update an existing Windows image. (Recommended)
• Manually copy the boot.stl file from the device Windows\Boot\EFI folder to the corresponding folder on your installation media before deploying the update.

For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.

Install this update

To install this update, use one of the following Windows and Microsoft release channels.

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File information

A list of the files included in this update is provided in a CSV (comma-delimited) (.csv) file. You can open the file in a text editor, such as Notepad, or in Microsoft Excel.

Note: The English (United States) version of this software update might contain files for additional languages.

Download the file information for cumulative update KB5131090. 

Download the file information for the SSU KB5131089 - version 20348.5859.

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