Microsoft fixed 164 problems in Office this month. Some of them let a bad Word, Excel or Outlook file take over your computer when you open it. Microsoft has not said that hackers are using the Office bugs yet. Update Office to be safe.
- Status
- Patched: update now
- Being attacked?
- No[1]
- Severity
- High
- Updated
Microsoft's October 2026 notes name only one attacked bug (the Windows one). None of the Office fixes are marked as attacked. Severity: Microsoft lists many bugs in Word, Excel, Outlook and PowerPoint that can run a program when you open a bad file (Tenable's scanner notes list them). First reported .
Am I affected?
You are at risk if you use Word, Excel, Outlook, PowerPoint or OneNote and have not updated Office since early October 2026.
| App | Device | Affected | Fixed in |
|---|---|---|---|
| Microsoft Office (Word, Excel, Outlook, PowerPoint) | Windows | Microsoft 365 / Office on Windows that has not installed the October 2026 update | Fixed in the October 2026 Office updates (Microsoft Update Guide lists the version).[1] |
| Microsoft Office (Word, Excel, Outlook, PowerPoint) | Mac | Office for Mac that has not installed the October 2026 update | Fixed in the October 2026 Office updates for Mac. Microsoft's Update Guide lists the version.[1] |
How to check your version
These checks only look. They do not change anything on your computer.
Microsoft Office (Word, Excel, Outlook, PowerPoint) on Windows
Easy way: Open Word (or Excel). Click File > Account > Update Options > Update Now. The version is shown under About Word.
Or type this in PowerShellRead-only. It only reads the version and changes nothing.
(Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Office\ClickToRun\Configuration' -ErrorAction SilentlyContinue).VersionToReport
Microsoft Office (Word, Excel, Outlook, PowerPoint) on Mac
Easy way: Open Word. Menu bar: Word > About Word. Or Word > Check for Updates.
Or type this in TerminalRead-only. It only reads the version and changes nothing.
defaults read "/Applications/Microsoft Word.app/Contents/Info" CFBundleShortVersionString
How to fix it
- Open Word or Excel.
- Windows: click File > Account > Update Options > Update Now.
- Mac: click Help > Check for Updates, then Update.
- Close and open Office again when it finishes.
- Do not open Office files from people you do not know until you have updated.
More on each app: Is my Microsoft Office up to date?
Official links
Check before installing, and only use these official links or the app's own update button.
For AI agents
This page as data: /incidents/office-october-2026-updates.json. All problems: /feed.json. Use read-only checks only, and ask before installing anything.
Tracking numbers (CVE): None
Sources
- MakerMicrosoft: October 2026 Security Updates release notes (164 Office fixes) (Oct 13, 2026)
- ResearcherTenable: Office C2R October 2026 security updates (list of bugs) (October 2026)
"Maker", "CISA", "NVD", "GitHub advisory" and "Official notice" are official sources. "Researcher" and "News" are extra context.