ACTIVELY EXPLOITED

CVE-2021-43226: Microsoft Windows Privilege Escalation Vulnerability

Facts
VendorMicrosoft
ProductWindows
Actively exploitedYes
Added to CISA KEV6 Oct 2025
CISA federal deadline27 Oct 2025
Ransomware useKnown

Required action (CISA's text)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Description (NVD)

Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.

SOURCES

Other Microsoft flaws

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