Heap-based buffer overflow in Microsoft products - CVE-2026-116927
Published: November 11, 2026
Vulnerability identifier: #VU164990
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-2026-116927
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 victim user's context.
The vulnerability exists due to a heap-based buffer overflow in Microsoft Office Excel when processing a specially crafted file that a user opens and saves as a web page. A remote attacker can send such a file and convince a user to open it in Excel and save it as a web page to execute arbitrary code in the user's context.
The Preview Pane is not an attack vector for this vulnerability.
Affected software
Microsoft Office for macOS
Microsoft Office
Office Online Server
Microsoft Office
Office Online Server
How to mitigate CVE-2026-116927
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