All vulnerabilities
CVE-2021-43226

Microsoft Windows Privilege Escalation Vulnerability

Microsoft WindowsOperating systems
Open in ThreatlineRecord JSON
CVSS
7.8High
ExploitationExploited in the wildAdded to KEV 6 Oct 2025. Known ransomware useCISA KEV
Exploit odds (EPSS)3.28%Chance of exploitation activity in the next 30 days, higher than 88% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in10.0.17763.2366Also 10.0.18363.1977, 10.0.19043.1415 and 12 moreCVE List
Federal deadline27 Oct 2025Remediation due date for US federal agenciesCISA KEV
CISA 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. CISA KEV

What fixes it

  • 10.0.17763.2366Windows 10 Version 1809CVE List
  • 10.0.17763.2366Windows Server 2019CVE List
  • 10.0.17763.2366Windows Server 2019 (Server Core installation)CVE List
  • 10.0.18363.1977Windows 10 Version 1909CVE List
  • 10.0.19043.1415Windows 10 Version 21H1CVE List
  • 10.0.20348.405Windows Server 2022CVE List
Show all 30 fixed versions
  • 10.0.19041.1415Windows 10 Version 2004CVE List
  • 10.0.19041.1415Windows Server version 2004CVE List
  • 10.0.19042.1415Windows 10 Version 20H2CVE List
  • 10.0.19042.1415Windows Server version 20H2CVE List
  • 10.0.22000.376Windows 11 version 21H2CVE List
  • 10.0.19044.1415Windows 10 Version 21H2CVE List
  • 10.0.10240.19145Windows 10 Version 1507CVE List
  • 10.0.14393.4825Windows 10 Version 1607CVE List
  • 10.0.14393.4825Windows Server 2016CVE List
  • 10.0.14393.4825Windows Server 2016 (Server Core installation)CVE List
  • 6.1.7601.25796Windows 7CVE List
  • 6.1.7601.25796Windows 7 Service Pack 1CVE List
  • 6.3.9600.20207Windows 8.1CVE List
  • 6.0.6003.21309Windows Server 2008 Service Pack 2CVE List
  • 6.0.6003.21309Windows Server 2008 Service Pack 2 (Server Core installation)CVE List
  • 6.0.6003.21309Windows Server 2008 Service Pack 2CVE List
  • 6.1.7601.25796Windows Server 2008 R2 Service Pack 1CVE List
  • 6.1.7601.25796Windows Server 2008 R2 Service Pack 1 (Server Core installation)CVE List
  • 6.2.9200.23545Windows Server 2012CVE List
  • 6.2.9200.23540Windows Server 2012CVE List
  • 6.2.9200.23545Windows Server 2012 (Server Core installation)CVE List
  • 6.2.9200.23540Windows Server 2012 (Server Core installation)CVE List
  • 6.3.9600.20207Windows Server 2012 R2CVE List
  • 6.3.9600.20207Windows Server 2012 R2 (Server Core installation)CVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 15 Dec 2021, 14:15 UTCPublishedCVE List
  2. 6 Oct 2025Added to CISA KEVCISA KEV

Description

Microsoft Windows Common Log File System Driver contains a privilege escalation vulnerability that could allow a local, privileged attacker to bypass certain security mechanisms.

Text from CVE List

Affected versions 30

  • Windows 10 Version 1809affected: 10.0.0 before 10.0.17763.2366CVE List
  • Windows Server 2019affected: 10.0.0 before 10.0.17763.2366CVE List
  • Windows Server 2019 (Server Core installation)affected: 10.0.0 before 10.0.17763.2366CVE List
  • Windows 10 Version 1909affected: 10.0.0 before 10.0.18363.1977CVE List
  • Windows 10 Version 21H1affected: 10.0.0 before 10.0.19043.1415CVE List
  • Windows Server 2022affected: 10.0.0 before 10.0.20348.405CVE List
  • Windows 10 Version 2004affected: 10.0.0 before 10.0.19041.1415CVE List
  • Windows Server version 2004affected: 10.0.0 before 10.0.19041.1415CVE List
  • Windows 10 Version 20H2affected: 10.0.0 before 10.0.19042.1415CVE List
  • Windows Server version 20H2affected: 10.0.0 before 10.0.19042.1415CVE List
  • Windows 11 version 21H2affected: 10.0.0 before 10.0.22000.376CVE List
  • Windows 10 Version 21H2affected: 10.0.0 before 10.0.19044.1415CVE List
  • Windows 10 Version 1507affected: 10.0.0 before 10.0.10240.19145CVE List
  • Windows 10 Version 1607affected: 10.0.0 before 10.0.14393.4825CVE List
  • Windows Server 2016affected: 10.0.0 before 10.0.14393.4825CVE List
  • Windows Server 2016 (Server Core installation)affected: 10.0.0 before 10.0.14393.4825CVE List
  • Windows 7affected: 6.1.0 before 6.1.7601.25796CVE List
  • Windows 7 Service Pack 1affected: 6.1.0 before 6.1.7601.25796CVE List
  • Windows 8.1affected: 6.3.0 before 6.3.9600.20207CVE List
  • Windows Server 2008 Service Pack 2affected: 6.0.0 before 6.0.6003.21309CVE List
  • Windows Server 2008 Service Pack 2 (Server Core installation)affected: 6.0.0 before 6.0.6003.21309CVE List
  • Windows Server 2008 Service Pack 2affected: 6.0.0 before 6.0.6003.21309CVE List
  • Windows Server 2008 R2 Service Pack 1affected: 6.1.0 before 6.1.7601.25796CVE List
  • Windows Server 2008 R2 Service Pack 1 (Server Core installation)affected: 6.0.0 before 6.1.7601.25796CVE List
  • Windows Server 2012affected: 6.2.0 before 6.2.9200.23545CVE List
  • Windows Server 2012affected: 6.2.0 before 6.2.9200.23540CVE List
  • Windows Server 2012 (Server Core installation)affected: 6.2.0 before 6.2.9200.23545CVE List
  • Windows Server 2012 (Server Core installation)affected: 6.2.0 before 6.2.9200.23540CVE List
  • Windows Server 2012 R2affected: 6.3.0 before 6.3.9600.20207CVE List
  • Windows Server 2012 R2 (Server Core installation)affected: 6.3.0 before 6.3.9600.20207CVE List

References 4