CVE intelligence

CVE-2026-83991

Vulnerability intelligence

Published Sep 8, 2026Sources checked Sep 12, 2026

5.5MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2026-83991 and is rated Medium severity with a CVSS score of 5.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-83991?

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