Main Vulnerability Database Vulnerabilities #VU137938

Improper Certificate Validation in Microsoft Windows and Windows Server - CVE-2026-55001

Published: July 17, 2026

Vulnerability identifier: #VU137938

CSH Severity: Low

CVSS v4: 6.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-55001

CWE-ID: CWE-295

Exploitation vector: Local access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to escalate privileges.

The vulnerability exists due to improper certificate validation in Windows Active Directory when validating certificates. A local user can present a certificate that is improperly validated to escalate privileges.

Successful exploitation could lead to administrator privileges.

Affected software

Microsoft Windows
Windows Server

How to mitigate CVE-2026-55001

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, 2016 10.0.14393.9339, 2019 10.0.17763.9020, 2022 10.0.20348.5386, 2025 10.0.26100.33158

External References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2026-55001

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