High severity · published Dec 15, 2021
CVE-2021-43226
Windows Common Log File System Driver Elevation of Privilege Vulnerability
RansomwareIn wildKEV
7.8
CVSS
3.3%
EPSS
Yes
On KEV
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)3.3% · higher than 88% of CVEs
Exploited in the wildYes
CISA KEVListed Oct 6, 2025
Federal remediation dueOct 27, 2025
Ransomware campaign useKnown
Affected products
Which versions
WI
Windows · Microsoft
All versions, or not specified · source: KEV
W1
Windows 10 Version 1507 · Microsoft
10.0.0 before 10.0.10240.19145 · source: vendor
W1
Windows 10 Version 1607 · Microsoft
10.0.0 before 10.0.14393.4825 · source: vendor
W1
Windows 10 Version 1809 · Microsoft
10.0.0 before 10.0.17763.2366 · source: vendor
W1
Windows 10 Version 1909 · Microsoft
10.0.0 before 10.0.18363.1977 · source: vendor
W1
Windows 10 Version 2004 · Microsoft
10.0.0 before 10.0.19041.1415 · source: vendor
W1
Windows 10 Version 20H2 · Microsoft
10.0.0 before 10.0.19042.1415 · source: vendor
W1
Windows 10 Version 21H1 · Microsoft
10.0.0 before 10.0.19043.1415 · source: vendor
W1
Windows 10 Version 21H2 · Microsoft
10.0.0 before 10.0.19044.1415 · source: vendor
W1
Windows 11 version 21H2 · Microsoft
10.0.0 before 10.0.22000.376 · source: vendor
W7
Windows 7 · Microsoft
6.1.0 before 6.1.7601.25796 · source: vendor, NVD
W7
Windows 7 Service Pack 1 · Microsoft
6.1.0 before 6.1.7601.25796 · source: vendor
In the news
VulnerabilityHigh
[CISA KEV] CVE-2021-43226: Microsoft Windows - Microsoft Windows Privilege Escalation Vulnerability
Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.
WIWindowsCVE-2021-43226
Oct 6, 2025·CISA KEV
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-43226
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-43226
CISA KEV catalogue
https://www.cisa.gov/known-exploited-vulnerabilities-catalog
x_refsource_MISC
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226
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