Stack-based buffer overflow in Microsoft products - CVE-2026-118731
Published: November 11, 2026
Vulnerability identifier: #VU165138
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-2026-118731
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code with the victim user's privileges.
The vulnerability exists due to a stack-based buffer overflow in Microsoft Office Excel when processing a specially crafted workbook. A remote attacker can convince a user to open the workbook, activate its embedded chart, and use Decrease Decimal on a cell in the chart's datasheet to execute arbitrary code with the user's privileges.
The Preview Pane is not an exploitation vector.
Affected software
Microsoft Office for macOS
Microsoft Office
Office Online Server
Microsoft Office
Office Online Server
How to mitigate CVE-2026-118731
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