Heap-based buffer overflow in Microsoft products - CVE-2026-120786
Published: November 11, 2026
Vulnerability identifier: #VU165418
CSH Severity: High
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-120786
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code in the context of the signed-in user.
The vulnerability exists due to a heap-based buffer overflow in Microsoft Office Excel when processing a specially crafted workbook and handling interaction with affected workbook features. A remote attacker can convince a user to open the workbook and interact with those features to execute arbitrary code in the context of the signed-in user.
The Preview Pane is not an attack vector.
Affected software
Microsoft Office for macOS
Microsoft Office
Office Online Server
Microsoft Office
Office Online Server
How to mitigate CVE-2026-120786
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.115.26110837
Office Online Server - update to 16.0.10417.20236
Microsoft Office - addressed in versions 16.0.14334.21048, 16.0.17932.21140
Office Online Server - update to 16.0.10417.20236
Microsoft Office - addressed in versions 16.0.14334.21048, 16.0.17932.21140