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Office Online Server OOS Office Online Server Security update
Patch Tuesday

KB5002679

KB5002679: Cumulative update for Office Online Server, version OOS, February 2025. Excel remote code execution vulnerability resolved

In short

Resolves a Microsoft Excel remote code execution vulnerability in Office Online Server. It addresses five vulnerabilities, including one rated Critical.

Does it affect you? Applies to: Organizations running the release version of Microsoft Office Online Server. The standalone package is for the 64-bit version.

Build
16.0.10416.20058
Security
5 fixed · 1 critical
Restart
Required

What changes

Fix 1 change

Excel

Verified in package
  • The Microsoft Excel remote code execution vulnerability is resolved.1
    Addresses CVE-2025-21381.

Technical details

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

Data sheet

Released
2025-02-11
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5002677, KB5002648, KB5002601, KB5002503
Replaced by
KB5002690
VersionBuildChannel
OOS 16.0.10416.20058 General availability

Security

5 vulnerabilities fixed
1 critical 4 important
VulnerabilitySeverityCVSS
CVE-2025-21381
Microsoft Excel Remote Code Execution Vulnerability
 Critical 7.8
CVE-2025-21386
Microsoft Excel Remote Code Execution Vulnerability
 Important 7.8
CVE-2025-21387
Microsoft Excel Remote Code Execution Vulnerability
 Important 7.8
CVE-2025-21390
Microsoft Excel Remote Code Execution Vulnerability
 Important 7.8
CVE-2025-21394
Microsoft Excel Remote Code Execution Vulnerability
 Important 7.8

Downloads (Microsoft Update Catalog)

Package OOS
1.0 GB
wacserver-x-none.cab Main update · KB5002679 SHA-1: 77bdd40e…e36d3c

Updated components

1,600 files changed since the previous update for the same versions.

Top changed componentsFiles
Office web apps369
PowerPoint324
Excel261
Document conversion74
Word50

Verified in package: changed files confirm Excel.

Sources

Updated
Cited passages from Microsoft's official notes (1)
  1. 1. This security update resolves a Microsoft Excel remote code execution vulnerability. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 1 quoted passage · compared with Microsoft's page on Oct 20, 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: not 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