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

High severity, CVSS 7.8. Actively exploited: in CISA KEV since 2021-11-03. EPSS: 4.1% 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 10.0.10240.19060 (fixed in 10.0.10240.19060)
• Microsoft Windows 10 1607: before 10.0.14393.4651 (fixed in 10.0.14393.4651)
• Microsoft Windows 10 1809: before 10.0.17763.2183 (fixed in 10.0.17763.2183)
• Microsoft Windows 10 1909: before 10.0.18363.1801 (fixed in 10.0.18363.1801)
• Microsoft Windows 10 2004: before 10.0.19041.1237 (fixed in 10.0.19041.1237)
• Microsoft Windows 10 20h2: before 10.0.19042.1237 (fixed in 10.0.19042.1237)
• Microsoft Windows 10 21h1: before 10.0.19043.1237 (fixed in 10.0.19043.1237)
• 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 10.0.19041.1237 (fixed in 10.0.19041.1237)
• Microsoft Windows Server 2008: affected versions not specified; version r2 only
• Microsoft Windows Server 2012: affected versions not specified
• Microsoft Windows Server 2016: before 10.0.14393.4651 (fixed in 10.0.14393.4651)
• Microsoft Windows Server 2019: before 10.0.17763.2183 (fixed in 10.0.17763.2183)
• Microsoft Windows Server 2022: before 10.0.20348.230 (fixed in 10.0.20348.230)
• Microsoft Windows Server 20h2: before 10.0.19042.1237 (fixed in 10.0.19042.1237)

Published 2021-09-15. Last modified 2026-08-10.