MSRC-CVE-2026-20857 — Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability

Summary

Impact: Elevation of Privilege. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. Customer action: Required.

Details

What privileges could be gained by an attacker who successfully exploited the vulnerability?
An attacker who successfully exploited this vulnerability could gain specific limited SYSTEM privileges.

Security updates
10.0.26200.7623 — https://support.microsoft.com/help/5074109
10.0.17763.8276 — https://support.microsoft.com/help/5073723
10.0.20348.4648 — https://support.microsoft.com/help/5073457
10.0.19044.6809 — https://support.microsoft.com/help/5073724
10.0.26100.32230 — https://support.microsoft.com/en-us/topic/a6021fd2-b3b7-45a7-b68e-35c28a2a77da
10.0.22631.6491 — https://support.microsoft.com/help/5073455
10.0.25398.2092 — https://support.microsoft.com/help/5073450

Vulnerabilities 1

High 7.8

CVE-2026-20857

Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability

Untrusted pointer dereference in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.

Microsoft Windows Server 2019 Windows Server 2019 (Server Core installation) Windows 10 Version 1809 Windows

Jan 13, 2026

Revision history

2026-01-13 #1
Information published.

References

CVE-2026-20857 Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20857
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
Common Vulnerability Scoring System
https://www.first.org/cvss