Time-of-check Time-of-use (TOCTOU) Race Condition in Microsoft 365 Apps for Enterprise - CVE-2026-97774
Published: October 14, 2026 / Updated: October 14, 2026
Vulnerability identifier: #VU155596
CSH Severity: Low
CVSS v4: 7.3 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-97774
CWE-ID: CWE-367
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to gain SYSTEM privileges.
The vulnerability exists due to a time-of-check time-of-use (TOCTOU) race condition in Microsoft Office Click-To-Run when accessed from an established foothold on the local system. A local user can win the race condition and escape the Protected View sandbox to gain SYSTEM privileges.
Affected software
Microsoft 365 Apps for Enterprise
How to mitigate CVE-2026-97774
Install security update from vendor's website.
Microsoft 365 Apps for Enterprise - addressed in versions 16.0.20228.20274, 16.0.20228.20276, 16.0.20326.20230, 16.0.20326.20232, 16.0.20430.20178, 16.0.20430.20180, 16.0.20430.20182