CVE-2021-43226VulnerabilityPublished 10/06/2025Updated 10/24/2026
CVE-2021-43226: Microsoft Windows Privilege Escalation Vulnerability
Affects Microsoft WindowsSource CISA KEV
Severity
HighNo CVSS score published yet
- Exploitation
Actively exploited – in CISA KEV since 10/06/2025
- KEV deadline
- 10/27/2025
- Ransomware
- Used in ransomware campaigns
- EPSS
- 3.3% chance of exploitation in 30 days – higher than 88% of CVEs
What to do
CISA required action
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
Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.