CVE-2026-83991

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

  • Published Sep 8, 2026
  • CVSS 5.5 medium
  • 0.3% chance of exploitation in the next 30 days (EPSS)
  • A fix is available

Affected software

CVE-2026-83991 at the National Vulnerability Database