CVE-2021-43226

Microsoft Windows 10 Version 1809, Microsoft Windows Server 2019, Microsoft Windows Server 2019 (Server Core installation)

Published 15 Dec 2021 · updated 22 Aug 2026 · Analyzed

7.8 High · CVSS 3.1, NVD

Exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on 6 Oct 2025, with a remediation deadline of 27 Oct 2025 for US federal agencies. It has been used in ransomware campaigns.

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

Windows Common Log File System Driver Elevation of Privilege Vulnerability

References

portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226 · Patch, Vendor Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43226 · US Government Resource