Race condition in Microsoft Windows and Windows Server - CVE-2026-83666
Published: October 14, 2026
Vulnerability identifier: #VU154806
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-2026-83666
CWE-ID: CWE-362
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to escalate privileges to SYSTEM.
The vulnerability exists due to improper synchronization of a shared resource in Active Directory Certificate Services (AD CS) when executing concurrent operations. A local user can win a race condition to escalate privileges to SYSTEM.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-83666
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 1607 10.0.14393.9612, 10 1809 10.0.17763.9376
Windows Server - addressed in versions 2012 R2 6.3.9600.23470, 2012 6.2.9200.26434, 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650
Windows Server - addressed in versions 2012 R2 6.3.9600.23470, 2012 6.2.9200.26434, 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650