How severe is CVE-2021-43226?

CVE-2021-43226 has a CVSS 3.1 base score of 7.8 (HIGH). EPSS estimates a 3.1% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2021-43226: Windows Common Log File System Driver Elevation of

CISA Known Exploited Vulnerabilities

Microsoft Windows Privilege Escalation Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2025-10-06

Remediation due

2025-10-27

Ransomware

Known use

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.

CISA notes
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-43226 ; https://nvd.nist.gov/vuln/detail/CVE-2021-43226

Description

Windows Common Log File System Driver Elevation of Privilege Vulnerability

Severity

CVSS 3.1 · CNA7.8 HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
Microsoft	Windows 10 Version 1809	10.0.0 to <10.0.17763.2366
Microsoft	Windows Server 2019	10.0.0 to <10.0.17763.2366
Microsoft	Windows Server 2019 (Server Core installation)	10.0.0 to <10.0.17763.2366
Microsoft	Windows 10 Version 1909	10.0.0 to <10.0.18363.1977
Microsoft	Windows 10 Version 21H1	10.0.0 to <10.0.19043.1415
Microsoft	Windows Server 2022	10.0.0 to <10.0.20348.405
Microsoft	Windows 10 Version 2004	10.0.0 to <10.0.19041.1415
Microsoft	Windows Server version 2004	10.0.0 to <10.0.19041.1415
Microsoft	Windows 10 Version 20H2	10.0.0 to <10.0.19042.1415
Microsoft	Windows Server version 20H2	10.0.0 to <10.0.19042.1415
Microsoft	Windows 11 version 21H2	10.0.0 to <10.0.22000.376
Microsoft	Windows 10 Version 21H2	10.0.0 to <10.0.19044.1415
Microsoft	Windows 10 Version 1507	10.0.0 to <10.0.10240.19145
Microsoft	Windows 10 Version 1607	10.0.0 to <10.0.14393.4825
Microsoft	Windows Server 2016	10.0.0 to <10.0.14393.4825
Microsoft	Windows Server 2016 (Server Core installation)	10.0.0 to <10.0.14393.4825
Microsoft	Windows 7	6.1.0 to <6.1.7601.25796
Microsoft	Windows 7 Service Pack 1	6.1.0 to <6.1.7601.25796
Microsoft	Windows 8.1	6.3.0 to <6.3.9600.20207
Microsoft	Windows Server 2008 Service Pack 2	6.0.0 to <6.0.6003.21309
Microsoft	Windows Server 2008 Service Pack 2 (Server Core installation)	6.0.0 to <6.0.6003.21309
Microsoft	Windows Server 2008 Service Pack 2	6.0.0 to <6.0.6003.21309
Microsoft	Windows Server 2008 R2 Service Pack 1	6.1.0 to <6.1.7601.25796
Microsoft	Windows Server 2008 R2 Service Pack 1 (Server Core installation)	6.0.0 to <6.1.7601.25796
Microsoft	Windows Server 2012	6.2.0 to <6.2.9200.23545 6.2.0 to <6.2.9200.23540
Microsoft	Windows Server 2012 (Server Core installation)	6.2.0 to <6.2.9200.23545 6.2.0 to <6.2.9200.23540
Microsoft	Windows Server 2012 R2	6.3.0 to <6.3.9600.20207
Microsoft	Windows Server 2012 R2 (Server Core installation)	6.3.0 to <6.3.9600.20207

References

1 Links

Other references

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226

Record Details

Published

2021-12-15

Last updated

2026-08-22

Assigner (CNA)

microsoft

Credited to

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CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.