CVE-2026-108439: Microsoft Office Word Remote Code Execution Vulnerability

Overview

Severity

High (CVSS 8.8)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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-Oct

Released

2026-10-15

Last Updated

2026-10-15

Description

Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.

FAQ

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

Affected Products (9)

Microsoft Office

• Microsoft Office LTSC for Mac 2021
• Microsoft Office LTSC for Mac 2024
• Microsoft Office 365 for Mac
• Microsoft Office LTSC 2021 for 64-bit editions
• Microsoft Office LTSC 2021 for 32-bit editions
• Microsoft Office LTSC 2024 for 64-bit editions
• Microsoft Office LTSC 2024 for 32-bit editions
• Microsoft 365 Apps for Enterprise for 64-bit Systems
• Microsoft 365 Apps for Enterprise for 32-bit Systems

Security Updates (3)

• Release Notes
• Release Notes
• Release Notes

Acknowledgments

vietnq, namnp with <a href="https://x.com/vcslab">Viettel Cyber Security</a>

Revision History

• 2026-10-15: Information published.
• 2026-10-15: Information published. This CVE was addressed by updates that were released in October 2026, but the CVE was inadvertently omitted from the October 2026 Security Updates. This is an informational change only. Customers who have already installed the October 2026 updates do not need to take any further action.