How severe is CVE-2021-40450?

CVE-2021-40450 has a CVSS 3.1 base score of 7.8 (HIGH). EPSS estimates a 1.6% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

CVE-2021-40450: Win32k Elevation of Privilege Vulnerability

CISA Known Exploited Vulnerabilities

Microsoft Win32k Privilege Escalation Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2022-04-25

Remediation due

2022-05-16

Required action
Apply updates per vendor instructions.

CISA notes
https://nvd.nist.gov/vuln/detail/CVE-2021-40450

Description

Win32k Elevation of Privilege Vulnerability

Severity

CVSS 3.1 · CNA7.8 HIGH

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

SSVC · CISA-ADP

Exploitationactive

Automatableno

Technical impacttotal

Exploitation Context

as of October 15, 2026

All KEV statistics→

CISA added CVE-2021-40450 to the KEV catalog 194 days after its CVE record was published.
It is one of 391 Microsoft entries in the CISA KEV catalog, and one of 166 added in 2022.
Its current EPSS score (1.6%) is higher than that of 6% of CISA KEV entries.

Affected Products

Vendor	Product	Affected versions
Microsoft	Microsoft Windows 10 Version 1809	10.0.0 to <10.0.17763.2237
Microsoft	Microsoft Windows Server 2019	10.0.0 to <10.0.17763.2237
Microsoft	Microsoft Windows Server 2019 (Server Core installation)	10.0.0 to <10.0.17763.2237
Microsoft	Microsoft Windows 10 Version 1909	10.0.0 to <10.0.18363.1854
Microsoft	Microsoft Windows 10 Version 21H1	10.0.0 to <10.0.19043.1288
Microsoft	Microsoft Windows Server 2022	10.0.0 to <10.0.20348.288
Microsoft	Microsoft Windows 10 Version 2004	10.0.0 to <10.0.19041.1288
Microsoft	Microsoft Windows Server version 2004	10.0.0 to <10.0.19041.1288
Microsoft	Microsoft Windows 10 Version 20H2	10.0.0 to <10.0.19042.1288
Microsoft	Microsoft Windows Server version 20H2	10.0.0 to <10.0.19042.1288
Microsoft	Microsoft Windows 11 version 21H2	10.0.0 to <10.0.22000.258

References

1 Links

Other references

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40450

Record Details

Published

2021-10-13

Last updated

2025-10-21

Assigner (CNA)

microsoft

Credited to

More from Microsoft

All Microsoft CVEs→

CVE-2014-41137.8 HIGH

Microsoft Win32k Privilege Escalation Vulnerability

KEVEPSS 86.9%2014-10-15

CVE-2016-72557.8 HIGH

Microsoft Win32k Privilege Escalation Vulnerability

KEVEPSS 81.0%2016-11-10

CVE-2021-17327.8 HIGH

Windows Win32k Elevation of Privilege Vulnerability

MicrosoftKEVEPSS 78.4%2021-02-25

CVE-2019-14587.8 HIGH

Microsoft Win32k Privilege Escalation Vulnerability

MicrosoftKEVEPSS 74.4%2019-12-10

CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.