CVE-2026-83991

Windows Cloud Files Mini Filter Driver Tampering Vulnerability

Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.

Affected

Microsoft · Windows 10 Version 1809 · Windows 10 Version 21H2 · Windows 10 Version 22H2 · Windows 11 version 23H2 · Windows 11 Version 23H2 · Windows 11 Version 24H2

CVSS v3.1 MICROSOFT

5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS

0.30% chance of exploitation in the next 30 days, 22nd percentile

Published

2026-09-08

Updated

2026-10-14

Proof-of-concept exploits (1)

• karollooool/CVE-2026-83991-writeup-and-poc17★ · 2026-10-13

Security advisories

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83991

References

• CVE Record
• NVD entry

Related

• CVE-2026-50416