KB5002834

Description of the security update for SharePoint Server 2019: February 10, 2026 (KB5002834)

Applies To

SharePoint Server 2019

Summary

Important:

• If you're currently running SharePoint Workflow Manager, you must install the SharePoint Workflow Manager (KB5002799) to your farm before you install this cumulative update.

• If you're currently running the Classic version of Workflow Manager, you have to enable the debug flag in order to continue using it.

$farm = Get-SPFarm

$farm.ServerDebugFlags.Add(53601)

$farm.update()

iisreset

This security update resolves a Microsoft Word spoofing vulnerability and Microsoft Outlook spoofing vulnerability. To learn more about the vulnerabilities, see the following security advisories:

• Microsoft Common Vulnerabilities and Exposures CVE-2026-21511

• Microsoft Common Vulnerabilities and Exposures CVE-2026-21260

Notes:

• This is build 16.0.10417.20097 of the security update package.

• To apply this security update, you must have the release version of Microsoft SharePoint Server 2019 installed on the computer.

Improvements and fixes

This security update contains improvements and fixes for the following nonsecurity issue in SharePoint Server 2019:

• Fixes the GB18030-2022 China certification issue.

• Fixes an issue in which the w3wp process stops responding repeatedly.

• Fixes an issue in which Set-SPMachineKey can no longer be used to set machine keys after the September 2025 cumulative update is installed.

How to get and install the update

Method 1: Microsoft Update

This update is available from Microsoft Update. When you turn on automatic updating, this update will be downloaded and installed...