Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability
This high-severity Microsoft Server advisory covers CVE-2026-20857 affecting Windows Server 2019 (Server Core installation), Windows Server 2022, 23H2 Edition (Server Core installation), Windows Server 2025 (Server Core installation).
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Summary
Untrusted pointer dereference in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.
Affected products named by the advisory: Windows Server 2019; Windows Server 2019 (Server Core installation); Windows Server 2022; Windows Server 2022, 23H2 Edition (Server Core installation); and 2 more.
Affected products named by the advisory: Windows Server 2025 (Server Core installation).
- Windows 10 Version 1809 10.0.17763.0 before 10.0.17763.8276
- Windows 10 Version 21H2 10.0.19044.0 before 10.0.19044.6809
- Windows 10 Version 22H2 10.0.19045.0 before 10.0.19045.6809
- Windows 11 version 23H2 10.0.22631.0 before 10.0.22631.6491
- Windows 11 Version 23H2 10.0.22631.0 before 10.0.22631.6491
- Windows 11 Version 24H2 10.0.26100.0 before 10.0.26100.7623
- Windows 11 Version 25H2 10.0.26200.0 before 10.0.26200.7623
- Windows Server 2019 10.0.17763.0 before 10.0.17763.8276
- Windows Server 2019 (Server Core installation) 10.0.17763.0 before 10.0.17763.8276
- Windows Server 2022 10.0.20348.0 before 10.0.20348.4648
- Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0 before 10.0.25398.2092
- Windows Server 2025 10.0.26100.0 before 10.0.26100.32230
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
- 10.0.17763.8276
- 10.0.19044.6809
- 10.0.19045.6809
- 10.0.22631.6491
- 10.0.26100.7623
- 10.0.26200.7623
- 10.0.20348.4648
- 10.0.25398.2092
- 10.0.26100.32230
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation
Upgrade to a fixed release: 10.0.17763.8276, 10.0.19044.6809, 10.0.19045.6809, 10.0.22631.6491, 10.0.26100.7623, 10.0.26200.7623. That is the remediation for this advisory.
The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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