#VU121329 Improper access control in Windows and Windows Server - CVE-2026-20839

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Main Vulnerability Database Vulnerabilities #VU121329

#VU121329 Improper access control in Windows and Windows Server - CVE-2026-20839

Published: January 13, 2026


Vulnerability identifier: #VU121329
Vulnerability risk: Low
CVSSv4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-20839
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability: No public exploit available
Vulnerable software:
Windows
Windows Server
Software vendor:
Microsoft

Description

The vulnerability allows a local user to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions in Windows Client-Side Caching (CSC) Service. A local user can bypass implemented security restrictions and gain unauthorized access to sensitive information on the system.


Remediation

Install updates from vendor's website.

External links