Windows Common Log File System Driver Elevation of Privilege Vulnerability

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Summary

CVECVE-2021-43226
StatePUBLISHED
Assignermicrosoft
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-12-15 15:15:09 UTC
Updated2026-08-22 04:16:54 UTC
DescriptionWindows Common Log File System Driver Elevation of Privilege Vulnerability

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

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

EPSS: 0.030720000 probability, percentile 0.866210000 (date 2026-08-21)

CISA KEV: Listed on 2025-10-06; due 2025-10-27; ransomware use Known

Problem Types: NVD-CWE-noinfo | Elevation of Privilege | CWE-noinfo Not enough information

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1[email protected]Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
2.0[email protected]Primary4.6AV:L/AC:L/Au:N/C:P/I:P/A:P

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

CVSS v2.0 Breakdown

Access Vector
Local
Access Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:L/AC:L/Au:N/C:P/I:P/A:P

CISA Known Exploited Vulnerability

VendorMicrosoft
ProductWindows
NameMicrosoft Windows Privilege Escalation Vulnerability
Required ActionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Noteshttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-43226 ; https://nvd.nist.gov/vuln/detail/CVE-2021-43226

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Microsoft Windows 10 1507 All All All All
Operating System Microsoft Windows 10 1507 All All All All
Operating System Microsoft Windows 10 1607 All All All All
Operating System Microsoft Windows 10 1607 All All All All
Operating System Microsoft Windows 10 1809 All All All All
Operating System Microsoft Windows 10 1909 All All All All
Operating System Microsoft Windows 10 2004 All All All All
Operating System Microsoft Windows 10 20h2 All All All All
Operating System Microsoft Windows 10 20h2 All All All All
Operating System Microsoft Windows 10 21h1 All All All All
Operating System Microsoft Windows 10 21h2 All All All All
Operating System Microsoft Windows 11 21h2 All All All All
Operating System Microsoft Windows 7 - sp1 All All
Operating System Microsoft Windows 8.1 - All All All
Operating System Microsoft Windows Rt 8.1 - All All All
Operating System Microsoft Windows Server 2004 All All All All
Operating System Microsoft Windows Server 2008 - sp2 All All
Operating System Microsoft Windows Server 2008 - sp2 All All
Operating System Microsoft Windows Server 2008 r2 sp1 All All
Operating System Microsoft Windows Server 2012 - All All All
Operating System Microsoft Windows Server 2012 r2 All All All
Operating System Microsoft Windows Server 2016 All All All All
Operating System Microsoft Windows Server 2019 All All All All
Operating System Microsoft Windows Server 2022 All All All All
Operating System Microsoft Windows Server 20h2 All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Microsoft Windows 10 Version 1809 affected 10.0.0 10.0.17763.2366 custom 32-bit Systems, x64-based Systems, ARM64-based Systems
CNA Microsoft Windows Server 2019 affected 10.0.0 10.0.17763.2366 custom x64-based Systems
CNA Microsoft Windows Server 2019 Server Core Installation affected 10.0.0 10.0.17763.2366 custom x64-based Systems
CNA Microsoft Windows 10 Version 1909 affected 10.0.0 10.0.18363.1977 custom 32-bit Systems, x64-based Systems, ARM64-based Systems
CNA Microsoft Windows 10 Version 21H1 affected 10.0.0 10.0.19043.1415 custom x64-based Systems, ARM64-based Systems, 32-bit Systems
CNA Microsoft Windows Server 2022 affected 10.0.0 10.0.20348.405 custom x64-based Systems
CNA Microsoft Windows 10 Version 2004 affected 10.0.0 10.0.19041.1415 custom 32-bit Systems, ARM64-based Systems, x64-based Systems
CNA Microsoft Windows Server Version 2004 affected 10.0.0 10.0.19041.1415 custom x64-based Systems
CNA Microsoft Windows 10 Version 20H2 affected 10.0.0 10.0.19042.1415 custom 32-bit Systems, ARM64-based Systems
CNA Microsoft Windows Server Version 20H2 affected 10.0.0 10.0.19042.1415 custom x64-based Systems
CNA Microsoft Windows 11 Version 21H2 affected 10.0.0 10.0.22000.376 custom x64-based Systems, ARM64-based Systems
CNA Microsoft Windows 10 Version 21H2 affected 10.0.0 10.0.19044.1415 custom 32-bit Systems, ARM64-based Systems
CNA Microsoft Windows 10 Version 1507 affected 10.0.0 10.0.10240.19145 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows 10 Version 1607 affected 10.0.0 10.0.14393.4825 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows Server 2016 affected 10.0.0 10.0.14393.4825 custom x64-based Systems
CNA Microsoft Windows Server 2016 Server Core Installation affected 10.0.0 10.0.14393.4825 custom x64-based Systems
CNA Microsoft Windows 7 affected 6.1.0 6.1.7601.25796 custom 32-bit Systems
CNA Microsoft Windows 7 Service Pack 1 affected 6.1.0 6.1.7601.25796 custom x64-based Systems
CNA Microsoft Windows 8.1 affected 6.3.0 6.3.9600.20207 custom 32-bit Systems, x64-based Systems, ARM64-based Systems
CNA Microsoft Windows Server 2008 Service Pack 2 affected 6.0.0 6.0.6003.21309 custom 32-bit Systems
CNA Microsoft Windows Server 2008 Service Pack 2 Server Core Installation affected 6.0.0 6.0.6003.21309 custom 32-bit Systems, x64-based Systems
CNA Microsoft Windows Server 2008 Service Pack 2 affected 6.0.0 6.0.6003.21309 custom x64-based Systems
CNA Microsoft Windows Server 2008 R2 Service Pack 1 affected 6.1.0 6.1.7601.25796 custom x64-based Systems
CNA Microsoft Windows Server 2008 R2 Service Pack 1 Server Core Installation affected 6.0.0 6.1.7601.25796 custom x64-based Systems
CNA Microsoft Windows Server 2012 affected 6.2.0 6.2.9200.23545 custom x64-based Systems
CNA Microsoft Windows Server 2012 affected 6.2.0 6.2.9200.23540 custom x64-based Systems
CNA Microsoft Windows Server 2012 Server Core Installation affected 6.2.0 6.2.9200.23545 custom x64-based Systems
CNA Microsoft Windows Server 2012 Server Core Installation affected 6.2.0 6.2.9200.23540 custom x64-based Systems
CNA Microsoft Windows Server 2012 R2 affected 6.3.0 6.3.9600.20207 custom x64-based Systems
CNA Microsoft Windows Server 2012 R2 Server Core Installation affected 6.3.0 6.3.9600.20207 custom x64-based Systems

References

ReferenceSourceLinkTags
www.cisa.gov/known-exploited-vulnerabilities-catalog 134c704f-9b21-4f2e-91b3-4a467353bcc0 www.cisa.gov US Government Resource
Security Update Guide - Microsoft Security Response Center af854a3a-2127-422b-91ae-364da2661108 portal.msrc.microsoft.com Patch, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
CISA Known Exploited Vulnerabilities catalog CISA www.cisa.gov kev

Additional Advisory Data

SourceTimeEvent
ADP2025-10-06T00:00:00.000ZCVE-2021-43226 added to CISA KEV

Legacy QID Mappings

  • 91846 Microsoft Windows Security Update for December 2021

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