Should you update to Microsoft 365 Apps 2609 build 20430.20182?
Yes, this week. Microsoft 365 Apps 2609 build 20430.20182 is a security update Microsoft released on 13 Oct 2026 for Windows. It fixes 132 security flaws, 34 rated critical and 98 important by Microsoft.[1] None of them is known to be used in attacks.
It is the newest Microsoft 365 Apps release, so it’s the one to have.
Should you update?
Yes, this week. Microsoft rates 34 fixes critical, and attackers study each release to work out what it fixed. Every security update closes holes that become public the moment it ships, so the risk of staying on the old version only grows. Waiting a week to see if others hit problems is a common habit; with a security update it’s the wrong trade.
Is Microsoft 365 Apps 2609 build 20430.20182 safe to install?
Yes. It’s Microsoft’s own security release, and updates rarely go wrong; a backup makes it painless if one does. The one unsafe way to get it is from a link: Microsoft never sends updates by email, text or pop-up, so install it only from Office’s own Update Now (File → Account → Update Options).
What it fixes
Microsoft lists 132 security flaws, 34 rated critical and 98 important by Microsoft.[1] The 132 critical and important ones are:
| Flaw | Severity | What Microsoft calls it |
|---|---|---|
CVE-2026-70215 | Critical | Microsoft Office PowerPoint Remote Code Execution Vulnerability |
CVE-2026-70242 | Critical | Microsoft Office Outlook Remote Code Execution Vulnerability |
CVE-2026-70269 | Critical | Microsoft Office Word Remote Code Execution Vulnerability |
CVE-2026-70291 | Critical | Microsoft Office Outlook Remote Code Execution Vulnerability |
CVE-2026-70300 | Critical | Microsoft Office Word Remote Code Execution Vulnerability |
CVE-2026-88144 | Critical | Microsoft Office PowerPoint Remote Code Execution Vulnerability |
CVE-2026-88156 | Critical | Microsoft Office Outlook Remote Code Execution Vulnerability |
CVE-2026-88178 | Critical | Microsoft Office PowerPoint Remote Code Execution Vulnerability |
CVE-2026-88185 | Critical | Microsoft Office Word Remote Code Execution Vulnerability |
CVE-2026-88207 | Critical | Microsoft Office PowerPoint Remote Code Execution Vulnerability |
CVE-2026-97016 | Critical | Microsoft Office Outlook Remote Code Execution Vulnerability |
CVE-2026-97739 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97741 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97742 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97745 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97749 | Critical | Microsoft Office Outlook Remote Code Execution Vulnerability |
CVE-2026-97753 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97755 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97756 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97758 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97759 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97761 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97765 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97767 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97776 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97778 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-97780 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-100209 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-100210 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
CVE-2026-100211 | Critical | Microsoft Office Excel Remote Code Execution Vulnerability |
| and 102 more | ||
How to update, and how long it takes
Five to fifteen minutes. Your Office apps close while it installs.
- Open Word (or Excel or PowerPoint) and click File, then Account.In Outlook it’s File → Office Account.
- Click Update Options, then Update Now.Office downloads the update in the background. Close your Office apps when it asks; they reopen when it’s done.
To check it worked: File → Account in Word or Excel: under About it shows e.g. Version 2609 (Build 20430.20182 Click-to-Run). It should say 2609 build 20430.20182 or later.
2608 build 20326.20144 vs 2609 build 20430.20182
Microsoft 365 Apps 2608 build 20326.20144, released 8 Sep 2026, fixed 100 security flaws. Microsoft 365 Apps 2609 build 20430.20182 fixes 132 security flaws and includes the fixes before it, so going straight to 2609 build 20430.20182 gets you both.
- Before: Microsoft 365 Apps 2608 build 20326.20144, 8 Sep 2026, 100 security flaws
- After: none yet. This is the newest.
- Microsoft 365 Apps updates, every release and the latest version
- Updates, the latest version of everything HARD tracks
References
- ^ Microsoft. “Release notes for Microsoft Office security updates, October 13, 2026”, 13 Oct 2026.