CVE-2026-40418: Microsoft Office Click-To-Run Elevation of Privilege Vulnerability

Overview

Severity

High (CVSS 7.8)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Category

Elevation of Privilege

Exploit Status

Not Exploited

Exploitation Likelihood

Unlikely

Patch Tuesday

2026-May

Released

2026-05-12

Description

Use after free in Microsoft Office Click-To-Run allows an authorized attacker to elevate privileges locally.

FAQ

Is the Preview Pane an attack vector for this vulnerability? No, the Preview Pane is not an attack vector. What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Affected Products (8)

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 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

Acknowledgments

0ccbbf129444eb66344ccafb92b00df4

Revision History

• 2026-05-12: Information published.