Improper Authorization in Windows and Windows Server - CVE-2026-54121
Published: July 17, 2026
Vulnerability identifier: #VU138100
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: CVE-2026-54121
CWE-ID: CWE-285
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
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.
How to mitigate CVE-2026-54121
Install security update from vendor's website.