CVE-2026-78510: Microsoft Word Remote Code Execution Vulnerability
Overview
- Severity
- Critical (CVSS 9.8)
- CVSS Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
- Category
- Remote Code Execution
- Exploit Status
- Not Exploited
- Exploitation Likelihood
- Less Likely
- Patch Tuesday
- 2026-Sep
- Released
- 2026-09-08
Description
Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.
FAQ
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.
Are the updates for the Microsoft Office LTSC for Mac currently available?
The security update for Microsoft Office LTSC for Mac 2021 and 2024 are not immediately available. The updates will be released as soon as possible, and when they are available, customers will be notified via a revision to this CVE information.
Is the Preview Pane an attack vector for this vulnerability?
Yes, the Preview Pane is an attack vector.
Affected Products (13)
Microsoft Office
- Microsoft Office 2019 for 32-bit editions
- Microsoft Office 2019 for 64-bit editions
- Microsoft 365 Apps for Enterprise for 32-bit Systems
- Microsoft 365 Apps for Enterprise for 64-bit Systems
- Microsoft Office LTSC for Mac 2021
- Microsoft Office LTSC 2021 for 64-bit editions
- Microsoft Office LTSC 2021 for 32-bit editions
- Microsoft Office LTSC 2024 for 32-bit editions
- Microsoft Office LTSC 2024 for 64-bit editions
- Microsoft Office LTSC for Mac 2024
- Microsoft Office 2016 (32-bit edition)
- Microsoft Office 2016 (64-bit edition)
- Microsoft Office 365 for Mac
Security Updates (1)
Acknowledgments
Haifei Li with <a href="https://pub.expmon.com/">EXPMON</a>
Revision History
- 2026-09-08: Information published.