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SharePoint Server 2019 SharePoint Server 2019 Security update
Patch Tuesday

KB5002834

KB5002834: Cumulative update for SharePoint Server, version 2019, February 2026. Word and Outlook spoofing flaws fixed; web-process stalls addressed

In short

The update fixes two Important Word and Outlook spoofing flaws—tricks that make content appear to come from a trusted source—and addresses repeated SharePoint web-process stalls.

Does it affect you? Applies to: SharePoint Server 2019 farms with the release version installed.

Build
16.0.10417.20097
Security
2 fixed
Restart
Required

Microsoft ships this release as two packages: KB5002834, the update itself, and KB5002836 for the language packs. Install both on every server of the farm, then run the SharePoint Products Configuration Wizard.

What changes

Fixes 3 changes

GB18030-2022 China certification

  • The GB18030-2022 China certification issue is fixed.1

SharePoint Server

  • SharePoint's process for handling web requests no longer repeatedly stops responding.2
    Fixes repeated stops responding in the w3wp process.

Set-SPMachineKey

  • Administrators can use Set-SPMachineKey to set machine keys again after installing the September 2025 cumulative update.3
    Fixes an issue that prevented Set-SPMachineKey from setting machine keys after the September 2025 cumulative update.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2026-02-10
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5002825, KB5002816, KB5002803, KB5002796
+4 earlier KB5002775, KB5002769, KB5002754, KB5002741
Replaced by
KB5002845
VersionBuildChannel
2019 16.0.10417.20097 General availability

Security

2 vulnerabilities fixed
2 important
VulnerabilitySeverityCVSS
CVE-2026-21260
Microsoft Outlook Spoofing Vulnerability
 Important 7.5
CVE-2026-21511
Microsoft Outlook Spoofing Vulnerability
 Important 7.5

Updated components

436 files changed since the previous update for the same versions.

Top changed componentsFiles
Search44
Project Server23
Document conversion20
Client object model9
Access Services8
Document management and policies6
Managed metadata5
Office web apps3
PowerPoint3
PowerShell2
Publishing2
Translation Services2

Sources

Updated
Cited passages from Microsoft's official notes (3)
  1. 1. Fixes the GB18030-2022 China certification issue. support.microsoft.com
  2. 2. Fixes an issue in which the w3wp process stops responding repeatedly. support.microsoft.com
  3. 3. Fixes an issue in which Set-SPMachineKey can no longer be used to set machine keys after the September 2025 cumulative update is installed. support.microsoft.com
Checked automatically: 8 of 8 checks passed, 3 quoted passages · compared with Microsoft's page on Sep 26, 2026
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: passed

A second AI read the text against the sources: correctness 5/5, clarity 4/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake