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High 7.8Known exploited (CISA KEV)Published Dec 15, 2021
CVE-2021-43226Windows Common Log File System Driver Elevation of Privilege Vulnerability
Updated under an hour ago ()
Does this affect you?
It affects Microsoft Windows 10 Version 1809 and 21 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Oct 6, 2025; federal agencies had to remediate by Oct 27, 2025, and it is known to be used in ransomware. Treat that date as your deadline.
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Windows Common Log File System Driver Elevation of Privilege Vulnerability
- CVSS
- 7.8 HIGH (v3.1, CNA)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
- Weakness (CWE)
- Not given
- Known exploited
- Added to CISA KEV Oct 6, 2025; federal remediation due Oct 27, 2025; known ransomware useApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- EPSS (exploitation in the next 30 days)
- 3.28% (percentile 88)
- Assigned by
- microsoft
- NVD analysis
- Analyzed
- Record last updated
- Aug 22, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Microsoft Windows 10 Version 1809 microsoft:windows_10_1809 | from 10.0.0 before 10.0.17763.2366 | CNA record |
Microsoft Windows Server 2019 microsoft:windows_server_2019 | from 10.0.0 before 10.0.17763.2366 | CNA record |
Microsoft Windows 10 Version 1909 microsoft:windows_10_1909 | from 10.0.0 before 10.0.18363.1977 | CNA record |
Microsoft Windows 10 Version 21H1 microsoft:windows_10_21h1 | from 10.0.0 before 10.0.19043.1415 | CNA record |
Microsoft Windows Server 2022 microsoft:windows_server_2022 | from 10.0.0 before 10.0.20348.405 | CNA record |
Microsoft Windows Server version 2004 microsoft:windows_server_2004 | from 10.0.0 before 10.0.19041.1415 | CNA record |
Microsoft Windows 10 Version 20H2 microsoft:windows_10_20h2 | from 10.0.0 before 10.0.19042.1415 | CNA record |
Microsoft Windows Server version 20H2 microsoft:windows_server_20h2 | from 10.0.0 before 10.0.19042.1415 | CNA record |
Microsoft Windows 11 version 21H2 microsoft:windows_11_21h2 | from 10.0.0 before 10.0.22000.376 | CNA record |
Microsoft Windows 10 Version 21H2 microsoft:windows_10_21h2 | from 10.0.0 before 10.0.19044.1415 | CNA record |
Microsoft Windows 10 Version 1507 microsoft:windows_10_1507 | from 10.0.0 before 10.0.10240.19145 | CNA record |
Microsoft Windows 10 Version 1607 microsoft:windows_10_1607 | from 10.0.0 before 10.0.14393.4825 | CNA record |
Microsoft Windows Server 2016 microsoft:windows_server_2016 | from 10.0.0 before 10.0.14393.4825 | CNA record |
Microsoft Windows 7 microsoft:windows_7 | from 6.1.0 before 6.1.7601.25796 | CNA record |
Microsoft Windows 8.1 microsoft:windows_8.1 | from 6.3.0 before 6.3.9600.20207 | CNA record |
Microsoft Windows 8.1 microsoft:windows_rt_8.1 | from 6.3.0 before 6.3.9600.20207 | CNA record |
Microsoft Windows Server 2008 Service Pack 2 microsoft:windows_server_2008_sp2 | from 6.0.0 before 6.0.6003.21309 | CNA record |
Microsoft Windows Server 2008 R2 Service Pack 1 microsoft:windows_server_2008_r2 | from 6.1.0 before 6.1.7601.25796 | CNA record |
Microsoft Windows Server 2012 microsoft:windows_server_2012 | from 6.2.0 before 6.2.9200.23545; from 6.2.0 before 6.2.9200.23540 | CNA record |
Microsoft Windows Server 2012 R2 microsoft:windows_server_2012_r2 | from 6.3.0 before 6.3.9600.20207 | CNA record |
microsoft windows_10_1507 microsoft:windows_10_1507 | before 10.0.10240.19145; before 10.0.10240.19145 | NVD |
microsoft windows_10_1607 microsoft:windows_10_1607 | before 10.0.14393.4825; before 10.0.14393.4825 | NVD |
microsoft windows_10_1809 microsoft:windows_10_1809 | before 10.0.17763.2366 | NVD |
microsoft windows_10_1909 microsoft:windows_10_1909 | before 10.0.18363.1977 | NVD |
microsoft windows_10_2004 microsoft:windows_10_2004 | before 10.0.19041.1415 | NVD |
microsoft windows_10_20h2 microsoft:windows_10_20h2 | before 10.0.19042.1415; before 10.0.19042.1415 | NVD |
microsoft windows_10_21h1 microsoft:windows_10_21h1 | before 10.0.19043.1415 | NVD |
microsoft windows_10_21h2 microsoft:windows_10_21h2 | before 10.0.19044.1415 | NVD |
microsoft windows_11_21h2 microsoft:windows_11_21h2 | before 10.0.22000.376 | NVD |
microsoft windows_7 microsoft:windows_7 | all versions | NVD |
microsoft windows_8.1 microsoft:windows_8.1 | all versions | NVD |
microsoft windows_rt_8.1 microsoft:windows_rt_8.1 | all versions | NVD |
microsoft windows_server_2004 microsoft:windows_server_2004 | before 10.0.19041.1415 | NVD |
microsoft windows_server_2008 microsoft:windows_server_2008 | all versions; all versions; r2 | NVD |
microsoft windows_server_2012 microsoft:windows_server_2012 | all versions; r2 | NVD |
microsoft windows_server_2016 microsoft:windows_server_2016 | before 10.0.14393.4825 | NVD |
microsoft windows_server_2019 microsoft:windows_server_2019 | before 10.0.17763.2366 | NVD |
microsoft windows_server_2022 microsoft:windows_server_2022 | before 10.0.20348.405 | NVD |
microsoft windows_server_20h2 microsoft:windows_server_20h2 | before 10.0.19042.1415 | NVD |
References
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226x-refsource-misc, patch, vendor-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43226us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.