Integer underflow in Office Online Server and Microsoft Office - CVE-2026-97746
Published: October 14, 2026
Vulnerability identifier: #VU155569
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-2026-97746
CWE-ID: CWE-191
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 integer underflow in Microsoft Office Excel when processing a malicious Office file. A remote attacker can send a malicious Office file to a user and convince them to open it to execute arbitrary code.
The Preview Pane is not an attack vector.
Affected software
Office Online Server
Microsoft Office
Microsoft Office
How to mitigate CVE-2026-97746
Install security update from vendor's website.
Office Online Server - update to 16.0.10417.20228
Microsoft Office - addressed in versions 16.0.14334.20974, 16.0.17932.21056
Microsoft Office - addressed in versions 16.0.14334.20974, 16.0.17932.21056