October 6, 2025 · Applied Cybernetics Group
CVE-2021-43226 — Microsoft Windows
known ransomware use
Microsoft Windows Privilege Escalation Vulnerability
- Added to KEV
2025-10-06- Federal due date
2025-10-27- Vendor
- Microsoft
- Product
- Windows
- EPSS
- 87.0th percentile (score 0.031, as of
2026-09-16) - NVD CVSS v3.1
- 7.8 (HIGH)
- Ransomware use
- Known
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2021-43226
CISA short 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.
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.
NVD description
Windows Common Log File System Driver Elevation of Privilege Vulnerability