High severity · published Oct 13, 2026
CVE-2026-83666
Active Directory Certificate Services (AD CS) Elevation of Privilege Vulnerability
7.0
CVSS
0.2%
EPSS
No
On KEV
Description
Concurrent execution using shared resource with improper synchronization ('race condition') in Active Directory Certificate Services (AD CS) allows an authorized attacker to elevate privileges locally.
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
High
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 13% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
W1
Windows 10 Version 1607 · Microsoft
10.0.14393.0 before 10.0.14393.9612 · source: vendor
W1
Windows 10 Version 1809 · Microsoft
10.0.17763.0 before 10.0.17763.9376 · source: vendor
WS
Windows Server 2012 · Microsoft
6.2.9200.0 before 6.2.9200.26434 · source: vendor
WS
Windows Server 2012 (Server Core installation) · Microsoft
6.2.9200.0 before 6.2.9200.26434 · source: vendor
WS
Windows Server 2012 R2 · Microsoft
6.3.9600.0 before 6.3.9600.23470 · source: vendor
WS
Windows Server 2012 R2 (Server Core installation) · Microsoft
6.3.9600.0 before 6.3.9600.23470 · source: vendor
WS
Windows Server 2016 · Microsoft
10.0.14393.0 before 10.0.14393.9612 · source: vendor
WS
Windows Server 2016 (Server Core installation) · Microsoft
10.0.14393.0 before 10.0.14393.9612 · source: vendor
WS
Windows Server 2019 · Microsoft
10.0.17763.0 before 10.0.17763.9376 · source: vendor
WS
Windows Server 2019 (Server Core installation) · Microsoft
10.0.17763.0 before 10.0.17763.9376 · source: vendor
WS
Windows Server 2022 · Microsoft
10.0.20348.0 before 10.0.20348.5761 · source: vendor
WS
Windows Server 2025 · Microsoft
10.0.26100.0 before 10.0.26100.33650 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-83666
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-83666
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83666
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