CVE-2021-40450
HighExploitedPublic exploitWin32k Elevation of Privilege Vulnerability
Published Oct 12, 2021 · Updated Oct 30, 2025
Key Facts
Patch immediately- CVE-2021-40450 is a high-severity vulnerability (CVSS 7.8 v3.1) affecting Windows 10 1809 (Microsoft), Windows 10 1909 (Microsoft), Windows 10 2004 (Microsoft) and 7 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 25, 2022. Public exploit code is available.
- EPSS estimates a 1.6% probability of exploitation in the next 30 days.
- Fixed versions are available, including Windows 10 1809 10.0.17763.2237, Windows 10 1809 10.0.18363.1854, Windows 10 1809 10.0.19041.1288.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.8
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
1.6%
Higher than 75.1% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-40450 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Win32k Elevation of Privilege Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Apr 25, 2022 | May 16, 2022 | Not reported |
| Industry KEV feed | Apr 25, 2022 | May 16, 2022 | Not reported |
| CIRCL KEV | Apr 25, 2022 | May 16, 2022 | Not reported |
| ENISA EUVD | Apr 25, 2022 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
28 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Windows 10 1809Microsoft | 10.0.17763.2237, 10.0.18363.1854, 10.0.19041.1288 | 10.0.17763.2237 |
| Windows 10 1909Microsoft | 10.0.18363.1854 | 10.0.18363.1854 |
| Windows 10 2004Microsoft | See advisory | 10.0.19041.1288 |
| windows 10 20H2Microsoft | 10.0.19042.1288 | 10.0.19042.1288 |
| windows 10 21H1Microsoft | 10.0.19043.1288 | 10.0.19043.1288 |
Patched Releases
Windows 10 1809
10.0.17763.2237, 10.0.18363.1854, 10.0.19041.1288
Windows 10 1909
10.0.18363.1854
Windows 10 2004
10.0.19041.1288
windows 10 20H2
10.0.19042.1288
windows 10 21H1
10.0.19043.1288
windows 11 21H2
10.0.22000.258
Windows Server 2004
10.0.19041.1288
Windows Server 2019
10.0.17763.2237
Windows Server 2022
10.0.20348.288
windows server 20H2
10.0.19042.1288
Timeline
Publicly disclosed
Oct 12, 2021
Added to CISA KEV
Apr 25, 2022
Added to Industry KEV feed
Apr 25, 2022
Added to CIRCL KEV
Apr 25, 2022
Added to ENISA EUVD
Apr 25, 2022
Last updated
Oct 30, 2025
References
FAQ
Common Questions.
Win32k Elevation of Privilege Vulnerability
Affected: Windows 10 1809 (Microsoft) versions 10.0.17763.2237, 10.0.18363.1854, 10.0.19041.1288; Windows 10 1909 (Microsoft) versions 10.0.18363.1854; Windows 10 2004 (Microsoft), among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Apr 25, 2022.
Yes. It was added on Apr 25, 2022 with a federal remediation due date of May 16, 2022.
Public exploit code is available.
Fixed versions are available, including Windows 10 1809 10.0.17763.2237, Windows 10 1809 10.0.18363.1854, Windows 10 1809 10.0.19041.1288.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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