Is CVE-2021-40449 being actively exploited?

Yes. CVE-2021-40449 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added on November 17, 2021.

What is the CVSS score for CVE-2021-40449?

CVE-2021-40449 has a CVSS 3.1 base score of 7.8 (HIGH).

CVE-2021-40449

HIGH · CVSS 7.8CISA KEV: actively exploitedEPSS 74.1%EU EUVD: exploited

Win32k Elevation of Privilege Vulnerability

Key facts

CVSS score: 7.8 (v3.1)
Severity: HIGH
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-416
EPSS score: 74.1% (99th percentile)
In CISA KEV: Yes, added November 17, 2021
In EU EUVD: Yes (EUVD-2021-27626)
Published: October 13, 2021
NVD last modified: June 17, 2026
Status: Analyzed

CISA Known Exploited Vulnerability

Microsoft Windows Win32k Privilege Escalation Vulnerability

Added to the KEV catalog on November 17, 2021; federal remediation due December 1, 2021. Known to be used in ransomware campaigns.

EU Vulnerability Database (EUVD)

This vulnerability is also tracked by ENISA as EUVD-2021-27626 in the EU Vulnerability Database. ENISA flags it as known exploited. Last updated in EUVD on October 21, 2025.

View on the EU Vulnerability Database

Affected products

microsoft / windows 10 1507
microsoft / windows 10 1607
microsoft / windows 10 1809
microsoft / windows 10 1909
microsoft / windows 10 2004
microsoft / windows 10 20h2
microsoft / windows 10 21h1
microsoft / windows 11
microsoft / windows 11 21h2
microsoft / windows 7
microsoft / windows 8.1
microsoft / windows rt 8.1
microsoft / windows server 2004
microsoft / windows server 2008
microsoft / windows server 2008
microsoft / windows server 2012
microsoft / windows server 2012
microsoft / windows server 2016
microsoft / windows server 2019
microsoft / windows server 2022
microsoft / windows server 20h2

Certified products that may be affected

4 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.

Microsoft Windows 10 version 2004 (May 2020 Update), Microsoft Windows Server version 2004 (May 2020 Update) and others - Microsoft Corporation - Common Criteria 2020-50-INF-3671 - active
Microsoft Windows 10 version 1909 and Microsoft Windows Server version 1909 - Microsoft Corporation - Common Criteria 2019-47-INF-3134 - archived
Windows 7 BitLocker™ Drive Encryption - Microsoft Corporation - FIPS 140 1332 - historical
Microsoft Windows 7 Kernel Mode Cryptographic Primitives Library (cng.sys) - Microsoft Corporation - FIPS 140 1328 - historical

References

http://packetstormsecurity.com/files/164926/Win32k-NtGdiResetDC-Use-After-Free-Local-Privilege-Escalation.html(Exploit, Third Party Advisory, VDB Entry)
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40449(Patch, Vendor Advisory)
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40449(US Government Resource)

Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS

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