Improper Authorization in Microsoft Windows and Windows Server - CVE-2026-54121
Published: July 17, 2026
Vulnerability identifier: #VU138100
CSH Severity: Medium
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-54121
CWE-ID: CWE-285
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to escalate privileges.
The vulnerability exists due to improper authorization in Active Directory Certificate Services (AD CS) when processing certificate requests for manipulated machine account attributes. A remote user can manipulate attributes associated with a machine account and obtain a certificate that allows authentication as that machine via PKINIT to escalate privileges.
If a Domain Controller account can be targeted, the vulnerability may allow privileged Active Directory operations.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-54121
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 1607 10.0.14393.9339, 10 1809 10.0.17763.9020, 11 26H1 10.0.28000.2525
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158
Windows Server - addressed in versions 2012 R2 6.3.9600.23291, 2012 6.2.9200.26226, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158