Heap-based buffer overflow in Microsoft products - CVE-2026-81947
Published: September 9, 2026
Vulnerability identifier: #VU148295
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-2026-81947
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.
The vulnerability exists due to a heap-based buffer overflow in Microsoft Office Excel when opening a malicious Office file. A remote attacker can send a malicious Office file and convince a user to open it to execute arbitrary code.
The Preview Pane is not an attack vector.
Affected software
Microsoft Excel
Microsoft 365 Apps for Enterprise
Microsoft Office
Office Online Server
Microsoft 365 Apps for Enterprise
Microsoft Office
Office Online Server
How to mitigate CVE-2026-81947
Install security update from vendor's website.
Microsoft Excel - update to 16.0.5569.1003
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1003, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Office Online Server - update to 16.0.10417.20207
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1003, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Office Online Server - update to 16.0.10417.20207