Is CVE-2021-43226 actively exploited?

Yes. KEV Intelligence tracks CVE-2021-43226 as a known exploited vulnerability. Confidence is confirmed.

What exploitation activity has KEV Intelligence observed?

KEV Intelligence has not yet recorded sensor-observed exploitation attempts for CVE-2021-43226. Our sensors continue to monitor for activity targeting this CVE.

Which versions are affected?

CVE-2021-43226 affects Microsoft Windows 10 Version 1809 and 27 other products. KEV Intelligence lists 30 version rows; examples include 10.0.0 to < 10.0.17763.2366.

Yes. CVE-2021-43226 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. KEV Intelligence attested it 1 day ahead of CISA.

CVE-2021-43226 Exploited in the Wild — Windows 10 Version 1809, Windows Server 2019, Windows Server 2019 (Server Core installation), Windows 10 Version 1909, Windows 10 Version 21H1, Windows Server 2022, Windows 10 Version 2004, Windows Server version 2004, Windows 10 Version 20H2, Windows Server version 20H2, Windows 11 version 21H2, Windows 10 Version 21H2, Windows 10 Version 1507, Windows 10 Version 1607, Windows Server 2016, Windows Server 2016 (Server Core installation), Windows 7, Windows 7 Service Pack 1, Windows 8.1, Windows Server 2008 Service Pack 2, Windows Server 2008 Service Pack 2 (Server Core installation), Windows Server 2008 Service Pack 2, Windows Server 2008 R2 Service Pack 1, Windows Server 2008 R2 Service Pack 1 (Server Core installation), Windows Server 2012, Windows Server 2012 (Server Core installation), Windows Server 2012 R2, Windows Server 2012 R2 (Server Core installation)

Q: What is CVE-2021-43226?

CVE-2021-43226 is a vulnerability affecting Microsoft Windows 10 Version 1809 and 27 other products. Windows Common Log File System Driver Elevation of Privilege Vulnerability

Q: How should organizations remediate it?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Q: Is it in CISA KEV?

Yes. CVE-2021-43226 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. KEV Intelligence attested it 1 day ahead of CISA.

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-43226 is a vulnerability affecting Microsoft Windows 10 Version 1809 and 27 other products. Windows Common Log File System Driver Elevation of Privilege Vulnerability

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

Microsoft / Windows 10 Version 1809 affected before 10.0.17763.2366.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Windows Common Log File System Driver Elevation of Privilege Vulnerability

Vendor Product Affected Status

Microsoft Windows 10 Version 1809 Before 10.0.17763.2366 Affected

Microsoft Windows Server 2019 Before 10.0.17763.2366 Affected

Microsoft Windows Server 2019 (Server Core installation) Before 10.0.17763.2366 Affected

Microsoft Windows 10 Version 1909 Before 10.0.18363.1977 Affected

Microsoft Windows 10 Version 21H1 Before 10.0.19043.1415 Affected

Microsoft Windows Server 2022 Before 10.0.20348.405 Affected

Microsoft Windows 10 Version 2004 Before 10.0.19041.1415 Affected

Microsoft Windows Server version 2004 Before 10.0.19041.1415 Affected

Microsoft Windows 10 Version 20H2 Before 10.0.19042.1415 Affected

Microsoft Windows Server version 20H2 Before 10.0.19042.1415 Affected

Microsoft Windows 11 version 21H2 Before 10.0.22000.376 Affected

Microsoft Windows 10 Version 21H2 Before 10.0.19044.1415 Affected

Microsoft Windows 10 Version 1507 Before 10.0.10240.19145 Affected

Microsoft Windows 10 Version 1607 Before 10.0.14393.4825 Affected

Microsoft Windows Server 2016 Before 10.0.14393.4825 Affected

Microsoft Windows Server 2016 (Server Core installation) Before 10.0.14393.4825 Affected

Microsoft Windows 7 Before 6.1.7601.25796 Affected

Microsoft Windows 7 Service Pack 1 Before 6.1.7601.25796 Affected

Microsoft Windows 8.1 Before 6.3.9600.20207 Affected

Microsoft Windows Server 2008 Service Pack 2 Before 6.0.6003.21309 Affected

Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) Before 6.0.6003.21309 Affected

Microsoft Windows Server 2008 Service Pack 2 Before 6.0.6003.21309 Affected

Microsoft Windows Server 2008 R2 Service Pack 1 Before 6.1.7601.25796 Affected

Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) Before 6.1.7601.25796 Affected

Microsoft Windows Server 2012 Before 6.2.9200.23545 Affected

Published: 15 Dec 2021
Exploitation Reported: 01 Jun 2026
Attack vector: Local
Complexity: Low
Privileges: Low
User interaction: None

CVE References

CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-43226
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226 portal.msrc.microsoft.com · CVE Record https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CV...

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

Independent exploitation attestation added to the KEV Intelligence record.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

Learn about Pro API access

Source	Added
CVE First	2026-06-01 10:41 UTC
CISA	2026-06-02 14:05 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets: 0
User-Agents: 0

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

7.8 High

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

EPSS

3.1%

All CVSS Scores

CVSS v3.1 7.8 High

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

CVSS v2.0 4.6 Medium

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

Timeline

From disclosure to observed exploitation

02 Jun 2026
Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
01 Jun 2026
Added to KEV Intelligence KEV Feed

High-confidence, third-party attested exploitation
15 Dec 2021
CVE published

Vulnerability disclosed publicly
02 Nov 2021
CVE ID reserved

Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Evidence confidence and provenance
First-party sensor telemetry
PoC and scanner references
Affected versions and enrichment
Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2021-43226

Free JSON includes basic KEV fields

{
  "cve_id": "CVE-2021-43226",
  "confidence": "Confirmed",
  "cvss_score": 7.8,
  "cvss_estimated": false,
  "epss_score": 0.03072,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

CVE-2021-43226