ACTIVELY EXPLOITED

CVE-2021-36955: Microsoft Windows Common Log File System (CLFS) Driver Privilege Escalation Vulnerability

Facts
VendorMicrosoft
ProductWindows
Actively exploitedYes
Added to CISA KEV3 Nov 2021
CISA federal deadline17 Nov 2021
Ransomware useKnown

Required action (CISA's text)

Apply updates per vendor instructions.

Description (NVD)

Microsoft Windows Common Log File System (CLFS) driver contains an unspecified vulnerability that allows for privilege escalation.

SOURCES

Other Microsoft flaws

Data from NVD, CISA KEV, FIRST EPSS and vendor advisories. Updated 10 Nov 2026.