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Home / Threats / CVE-2026-20839

CVE-2026-20839 - Windows 10 Version 1607 Plugin

CVE-2026-20839

Vulnerability CVE-2026-20839 PLUGIN windows-10-version-1607 MEDIUM

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

CVE-2026-20839

MEDIUM CVSS 5.5 Published 2026-01-13 Updated 2026-01-15
AI Risk Moderate (48/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P4 Planned
Severity Band MEDIUM
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Affected Components 15
Reference Links 1
AI Risk Engine Moderate (48/100)
Exploitability Low
Active Exploitation No strong signal
Published Exploit Status No public exploit references

Threat Timeline

  1. 2026-01-13 CVE published and first recorded in the threat feed.
  2. 2026-01-15 Record updated with latest vulnerability metadata.
  3. 2026-04-09 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 12 days ago

AI enriched 12 days ago (2026-04-09 08:07 UTC)

Technical Summary

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

Potential Impact

Severity is MEDIUM (CVSS 5.5). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as Low based on severity and technical exposure profile.

Primary risk drivers: severity and technical exposure profile

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

Windows 10 Version 1607 PLUGIN · windows-10-version-1607 Affected: >= 10.0.14393.0, < 10.0.14393.8783 Fixed in: 10.0.14393.8783
Windows 10 Version 1809 PLUGIN · windows-10-version-1809 Affected: >= 10.0.17763.0, < 10.0.17763.8276 Fixed in: 10.0.17763.8276
Windows 10 Version 21H2 PLUGIN · windows-10-version-21h2 Affected: >= 10.0.19044.0, < 10.0.19044.6809 Fixed in: 10.0.19044.6809
Windows 10 Version 22H2 PLUGIN · windows-10-version-22h2 Affected: >= 10.0.19045.0, < 10.0.19045.6809 Fixed in: 10.0.19045.6809
Windows 11 version 22H3 PLUGIN · windows-11-version-22h3 Affected: >= 10.0.22631.0, < 10.0.22631.6491 Fixed in: 10.0.22631.6491
Windows 11 Version 23H2 PLUGIN · windows-11-version-23h2 Affected: >= 10.0.22631.0, < 10.0.22631.6491 Fixed in: 10.0.22631.6491
Windows 11 Version 24H2 PLUGIN · windows-11-version-24h2 Affected: >= 10.0.26100.0, < 10.0.26100.7623 Fixed in: 10.0.26100.7623
Windows 11 Version 25H2 PLUGIN · windows-11-version-25h2 Affected: >= 10.0.26200.0, < 10.0.26200.7623 Fixed in: 10.0.26200.7623
Windows Server 2008 R2 Service Pack 1 PLUGIN · windows-server-2008-r2-service-pack-1 Affected: >= 6.1.7601.0, < 6.1.7601.28117 Fixed in: 6.1.7601.28117
Windows Server 2012 PLUGIN · windows-server-2012 Affected: >= 6.2.9200.0, < 6.2.9200.25868 Fixed in: 6.2.9200.25868
Windows Server 2012 R2 PLUGIN · windows-server-2012-r2 Affected: >= 6.3.9600.0, < 6.3.9600.22968 Fixed in: 6.3.9600.22968
Windows Server 2016 PLUGIN · windows-server-2016 Affected: >= 10.0.14393.0, < 10.0.14393.8783 Fixed in: 10.0.14393.8783
Windows Server 2019 PLUGIN · windows-server-2019 Affected: >= 10.0.17763.0, < 10.0.17763.8276 Fixed in: 10.0.17763.8276
Windows Server 2022 PLUGIN · windows-server-2022 Affected: >= 10.0.20348.0, < 10.0.20348.4648 Fixed in: 10.0.20348.4648
Windows Server 2025 PLUGIN · windows-server-2025 Affected: >= 10.0.26100.0, < 10.0.26100.32230 Fixed in: 10.0.26100.32230

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CVE-2026-21265 - Windows 10 Version 1607 Plugin CVE-2026-21265 Published 2026-01-13 CVE-2026-20940 - Windows 10 Version 1607 Plugin CVE-2026-20940 Published 2026-01-13 CVE-2026-20939 - Windows 10 Version 1607 Plugin CVE-2026-20939 Published 2026-01-13 CVE-2026-20931 - Windows 10 Version 1607 Plugin CVE-2026-20931 Published 2026-01-13 CVE-2026-20934 - Windows 10 Version 1607 Plugin CVE-2026-20934 Published 2026-01-13 CVE-2026-20937 - Windows 10 Version 1607 Plugin CVE-2026-20937 Published 2026-01-13
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