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CVE-2026-20839: CWE-284: Improper Access Control in Microsoft Windows 10 Version 1607

0
Medium
VulnerabilityCVE-2026-20839cvecve-2026-20839cwe-284
Published: 01/13/2026 (01/13/2026, 17:56:26 UTC)
Source: CVE Database V5
Vendor/Project: Microsoft
Product: Windows 10 Version 1607

Description

Improper access control in Windows Client-Side Caching (CSC) Service allows an authorized attacker to disclose information locally.

CVSS v3.1

Score 5.5medium

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Affected software

Microsoft

Windows 10 Version 1607

Affected versions
>=10.0.14393.0 <10.0.14393.8783

Microsoft

Windows 10 Version 1809

Affected versions
>=10.0.17763.0 <10.0.17763.8276

Microsoft

Windows 10 Version 21H2

Affected versions
>=10.0.19044.0 <10.0.19044.6809

Microsoft

Windows 10 Version 22H2

Affected versions
>=10.0.19045.0 <10.0.19045.6809

Microsoft

Windows 11 version 23H2

Affected versions
>=10.0.22631.0 <10.0.22631.6491

Microsoft

Windows 11 Version 23H2

Affected versions
>=10.0.22631.0 <10.0.22631.6491

Microsoft

Windows 11 Version 24H2

Affected versions
>=10.0.26100.0 <10.0.26100.7623

Microsoft

Windows 11 Version 25H2

Affected versions
>=10.0.26200.0 <10.0.26200.7623

Microsoft

Windows Server 2008 R2 Service Pack 1

Affected versions
>=6.1.7601.0 <6.1.7601.28117

Microsoft

Windows Server 2008 R2 Service Pack 1 (Server Core installation)

Affected versions
>=6.1.7601.0 <6.1.7601.28117

Microsoft

Windows Server 2012

Affected versions
>=6.2.9200.0 <6.2.9200.25868

Microsoft

Windows Server 2012 (Server Core installation)

Affected versions
>=6.2.9200.0 <6.2.9200.25868

Microsoft

Windows Server 2012 R2

Affected versions
>=6.3.9600.0 <6.3.9600.22968

Microsoft

Windows Server 2012 R2 (Server Core installation)

Affected versions
>=6.3.9600.0 <6.3.9600.22968

Microsoft

Windows Server 2016

Affected versions
>=10.0.14393.0 <10.0.14393.8783

Microsoft

Windows Server 2016 (Server Core installation)

Affected versions
>=10.0.14393.0 <10.0.14393.8783

Microsoft

Windows Server 2019

Affected versions
>=10.0.17763.0 <10.0.17763.8276

Microsoft

Windows Server 2019 (Server Core installation)

Affected versions
>=10.0.17763.0 <10.0.17763.8276

Microsoft

Windows Server 2022

Affected versions
>=10.0.20348.0 <10.0.20348.4648

Microsoft

Windows Server 2022, 23H2 Edition (Server Core installation)

Affected versions
>=10.0.25398.0 <10.0.25398.2092

Microsoft

Windows Server 2025

Affected versions
>=10.0.26100.0 <10.0.26100.32230

Microsoft

Windows Server 2025 (Server Core installation)

Affected versions
>=10.0.26100.0 <10.0.26100.32230

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 07/30/2026, 23:46:44 UTC

Technical Analysis

This vulnerability involves improper access control in the Windows Client-Side Caching (CSC) Service on Windows 10 Version 1607 (build 10.0.14393.0). An attacker with legitimate local privileges can exploit this flaw to disclose information that should be protected. The issue does not require user interaction and affects confidentiality but not integrity or availability. Microsoft has published an official fix to address this vulnerability.

Potential Impact

An authorized local attacker can disclose sensitive information due to improper access control in the CSC Service. The confidentiality of data is impacted, but there is no impact on integrity or availability. There are no known exploits in the wild at this time.

Mitigation Recommendations

An official fix is available from Microsoft. Users and administrators should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20839 to remediate this vulnerability.

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Technical Details

Data Version
5.2
Assigner Short Name
microsoft
Date Reserved
2025-12-03T05:54:20.376Z
Cvss Version
3.1
State
PUBLISHED
Remediation Level
official-fix
Vendor Advisory Urls
[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20839","vendor":"Microsoft"}]

Threat ID: 69668adea60475309f9ae097

Added to database: 01/13/2026, 18:11:42 UTC

Last enriched: 07/30/2026, 23:46:44 UTC

Last updated: 09/10/2026, 22:26:02 UTC

Views: 308

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