CVE-2021-43226: Microsoft Windows Privilege Escalation Vulnerability

High severity, CVSS 7.8. Actively exploited: in CISA KEV since 2025-10-06. EPSS: 3.3% chance of exploitation in the next 30 days.

Windows Common Log File System Driver Elevation of Privilege Vulnerability

Affected products

• Microsoft Windows 10 1507: before 10.0.10240.19145 (fixed in 10.0.10240.19145)
• Microsoft Windows 10 1607: before 10.0.14393.4825 (fixed in 10.0.14393.4825)
• Microsoft Windows 10 1809: before 10.0.17763.2366 (fixed in 10.0.17763.2366)
• Microsoft Windows 10 1909: before 10.0.18363.1977 (fixed in 10.0.18363.1977)
• Microsoft Windows 10 2004: before 10.0.19041.1415 (fixed in 10.0.19041.1415)
• Microsoft Windows 10 20h2: before 10.0.19042.1415 (fixed in 10.0.19042.1415)
• Microsoft Windows 10 21h1: before 10.0.19043.1415 (fixed in 10.0.19043.1415)
• Microsoft Windows 10 21h2: before 10.0.19044.1415 (fixed in 10.0.19044.1415)
• Microsoft Windows 11 21h2: before 10.0.22000.376 (fixed in 10.0.22000.376)
• Microsoft Windows 7: affected versions not specified
• Microsoft Windows 8.1: affected versions not specified
• Microsoft Windows Rt 8.1: affected versions not specified
• Microsoft Windows Server 2004: before 10.0.19041.1415 (fixed in 10.0.19041.1415)
• Microsoft Windows Server 2008: affected versions not specified; version r2 only
• Microsoft Windows Server 2012: affected versions not specified; version r2 only
• Microsoft Windows Server 2016: before 10.0.14393.4825 (fixed in 10.0.14393.4825)
• Microsoft Windows Server 2019: before 10.0.17763.2366 (fixed in 10.0.17763.2366)
• Microsoft Windows Server 2022: before 10.0.20348.405 (fixed in 10.0.20348.405)
• Microsoft Windows Server 20h2: before 10.0.19042.1415 (fixed in 10.0.19042.1415)

Published 2021-12-15. Last modified 2026-08-22.