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Office Online Server OOS Office Online Server Security update
Patch Tuesday

KB5002677

KB5002677: Cumulative update for Office Online Server, version OOS, January 2025. Excel remote-code execution vulnerabilities addressed

In short

Addresses two critical Excel remote-code execution vulnerabilities, CVE-2025-21354 and CVE-2025-21362. It applies to the release version of Office Online Server.

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

Build
16.0.10416.20047
Security
2 fixed · 2 critical
Restart
Required

What changes

Fix 1 change

Microsoft Excel

For: Office Online Server administrators

  • The update resolves a remote code execution vulnerability in Excel.1
    Addresses CVE-2025-21354 and CVE-2025-21362.

Technical details

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

Data sheet

Released
2025-01-14
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5002648, KB5002601, KB5002503
Replaced by
KB5002679
VersionBuildChannel
OOS 16.0.10416.20047 General availability

Security

2 vulnerabilities fixed
2 critical
VulnerabilitySeverityCVSS
CVE-2025-21354
Microsoft Excel Remote Code Execution Vulnerability
 Critical 8.4
CVE-2025-21362
Microsoft Excel Remote Code Execution Vulnerability
 Critical 8.4

Downloads (Microsoft Update Catalog)

Package OOS
1.0 GB
wacserver-x-none.cab Main update · KB5002677 SHA-1: e1339723…c49f24

Updated components

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

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