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High 7.8Known exploited (CISA KEV)Published Oct 13, 2021
CVE-2021-40450Win32k Elevation of Privilege Vulnerability
Updated under an hour ago ()
Does this affect you?
It affects Microsoft Windows 10 Version 1809 and 9 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since Apr 25, 2022; federal agencies had to remediate by May 16, 2022. Treat that date as your deadline.
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Win32k 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 Apr 25, 2022; federal remediation due May 16, 2022Apply updates per vendor instructions.
- EPSS (exploitation in the next 30 days)
- 1.58% (percentile 75)
- Assigned by
- microsoft
- NVD analysis
- Analyzed
- Record last updated
- Oct 21, 2025
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Microsoft Windows 10 Version 1809 microsoft:windows_10_1809 | from 10.0.0 before 10.0.17763.2237 | CNA record |
Microsoft Windows Server 2019 microsoft:windows_server_2019 | from 10.0.0 before 10.0.17763.2237 | CNA record |
Microsoft Windows 10 Version 1909 microsoft:windows_10_1909 | from 10.0.0 before 10.0.18363.1854 | CNA record |
Microsoft Windows 10 Version 21H1 microsoft:windows_10_21h1 | from 10.0.0 before 10.0.19043.1288 | CNA record |
Microsoft Windows Server 2022 microsoft:windows_server_2022 | from 10.0.0 before 10.0.20348.288 | CNA record |
Microsoft Windows Server version 2004 microsoft:windows_server_2004 | from 10.0.0 before 10.0.19041.1288 | CNA record |
Microsoft Windows 10 Version 20H2 microsoft:windows_10_20h2 | from 10.0.0 before 10.0.19042.1288 | CNA record |
Microsoft Windows Server version 20H2 microsoft:windows_server_20h2 | from 10.0.0 before 10.0.19042.1288 | CNA record |
Microsoft Windows 11 version 21H2 microsoft:windows_11_21h2 | from 10.0.0 before 10.0.22000.258 | CNA record |
microsoft windows_10_1809 microsoft:windows_10_1809 | before 10.0.17763.2237 | NVD |
microsoft windows_10_1909 microsoft:windows_10_1909 | before 10.0.18363.1854 | NVD |
microsoft windows_10_2004 microsoft:windows_10_2004 | before 10.0.19041.1288 | NVD |
microsoft windows_10_20h2 microsoft:windows_10_20h2 | before 10.0.19042.1288 | NVD |
microsoft windows_10_21h1 microsoft:windows_10_21h1 | before 10.0.19043.1288 | NVD |
microsoft windows_11_21h2 microsoft:windows_11_21h2 | before 10.0.22000.258 | NVD |
microsoft windows_server_2004 microsoft:windows_server_2004 | before 10.0.19041.1288 | NVD |
microsoft windows_server_2019 microsoft:windows_server_2019 | before 10.0.17763.2237 | NVD |
microsoft windows_server_2022 microsoft:windows_server_2022 | before 10.0.20348.288 | NVD |
microsoft windows_server_20h2 microsoft:windows_server_20h2 | before 10.0.19042.1288 | NVD |
References
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40450x-refsource-misc, patch, vendor-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40450us-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.