Vulnerability · Published Sep 8, 2026 · Assigned by microsoft
CVE-2026-83991Windows Cloud Files Mini Filter Driver Tampering Vulnerability
Medium 5.5
In plain English
A medium-severity missing authentication in Windows 10 Version 1809 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Severity (CVSS 3.1)5.5Medium
Exploit odds (30 days)0.3%top 76.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC
Official description
Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 Version 1809 | 10.0.17763.0 – before 10.0.17763.9245 |
| Microsoft | Windows 10 Version 21H2 | 10.0.19044.0 – before 10.0.19044.7725 |
| Microsoft | Windows 10 Version 22H2 | 10.0.19045.0 – before 10.0.19045.7725 |
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 – before 10.0.22631.7582 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 – before 10.0.22631.7582 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 – before 10.0.26100.9445 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 – before 10.0.26200.9445 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – before 10.0.28000.2954 |
| Microsoft | Windows Server 2019 | 10.0.17763.0 – before 10.0.17763.9245 |
| Microsoft | Windows Server 2019 (Server Core installation) | 10.0.17763.0 – before 10.0.17763.9245 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – before 10.0.20348.5622 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.33438 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.33438 |
Weakness: CWE-306 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C
References
- Windows Cloud Files Mini Filter Driver Tampering Vulnerability vendor-advisory, patch