Description
Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Microsoft | Windows 10 Version 1809 | 10.0.17763.0 – < 10.0.17763.9245 | 10.0.17763.9245 |
| Microsoft | Windows 10 Version 21H2 | 10.0.19044.0 – < 10.0.19044.7725 | 10.0.19044.7725 |
| Microsoft | Windows 10 Version 22H2 | 10.0.19045.0 – < 10.0.19045.7725 | 10.0.19045.7725 |
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 – < 10.0.22631.7582 | 10.0.22631.7582 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 – < 10.0.26100.9445 | 10.0.26100.9445 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 – < 10.0.26200.9445 | 10.0.26200.9445 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – < 10.0.28000.2954 | 10.0.28000.2954 |
| Microsoft | Windows Server 2019 | 10.0.17763.0 – < 10.0.17763.9245 | 10.0.17763.9245 |
| Microsoft | Windows Server 2019 (Server Core installation) | 10.0.17763.0 – < 10.0.17763.9245 | 10.0.17763.9245 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – < 10.0.20348.5622 | 10.0.20348.5622 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – < 10.0.26100.33438 | 10.0.26100.33438 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – < 10.0.26100.33438 | 10.0.26100.33438 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
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karollooool/CVE-2026-83991-writeup-and-poc ★ 18 · Sep 9, 2026
CVE-2026-83991: Windows Cloud Files access-check bypass
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 2
- WID-SEC-2026-3243 Microsoft Windows: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 4, 2026
- MSRC-CVE-2026-83991 Windows Cloud Files Mini Filter Driver Tampering Vulnerability Microsoft Security Response Center · Sep 8, 2026
References
- Windows Cloud Files Mini Filter Driver Tampering Vulnerability vendor-advisory patch