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OpenAdvisories
Critical MSRC-CVE-2026-78510 1 CVE

Microsoft Outlook and Word Remote Code Execution Vulnerability

Published Sep 8, 2026 · Updated Sep 25, 2026 · Revision 4

Vendor: Microsoft

Summary

Impact: Remote Code Execution. Microsoft rating: Critical. Not known to be exploited — Exploitation Less Likely. Customer action: Required.

Details

How could an attacker exploit this vulnerability?
An unauthenticated attacker could exploit this vulnerability by crafting a malicious RTF file. If a user opens the file or it is rendered in the preview pane, the attacker could execute arbitrary code in the user's context.

Is the Preview Pane an attack vector for this vulnerability?
Yes, the Preview Pane is an attack vector.

Are the updates for Microsoft Office LTSC for Mac 2021 and 2024 currently available?
Yes. As of September 16, 2026, the security update for Microsoft Office LTSC for Mac 2021, 2024 and Microsoft Office 365 for Mac are available. Customers running Microsoft Office LTSC for Mac 2021, 2024 and Microsoft Office 365 for Mac should ensure the update is installed to be protected from this vulnerability.

Security updates
16.0.10417.20207 — https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
16.0.20326.20138 — https://docs.microsoft.com/en-us/officeupdates/office365-proplus-security-updates
16.113.26091433 — https://go.microsoft.com/fwlink/p/?linkid=831049
16.0.5569.1000 — https://support.microsoft.com/help/5002916
16.113.26091433 — https://www.microsoft.com/en-us/microsoft-365/mac/microsoft-365-for-mac?msockid=35f9adb0e74b61392038b90de6fe608c

Vulnerabilities 1

Revision history

  1. #4

    Updated CVE title and CVSS Score. This is an informational change only.

  2. #3

    Updated CVE title. This is an informational change only.

  3. #2

    Microsoft is announcing the availability of the security updates for Microsoft Office for Mac. Customers running affected Mac software should install the update for their product to be protected from this vulnerability. Customers running other Microsoft Office software do not need to take any action. See the [Release Notes](https://go.microsoft.com/fwlink/p/?linkid=831049) for more information and download links.

  4. #1

    Information published.

References