Is CVE-2021-40449 in the CISA KEV catalog?

Yes. CVE-2021-40449 is on the CISA Known Exploited Vulnerabilities list, added 2021-11-17, and has known ransomware campaign use.

What is the CVSS severity of CVE-2021-40449?

CVE-2021-40449 has a CVSS v3 base score of 7.8 (HIGH).

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

CVE-2021-40449 has an EPSS score of 73.38% (99th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-40449?

Install KB5006675 for Windows 10. Fixes are available for 25 affected products.

CVE & CISA-KEV Catalog

CVE-2021-40449

HIGHCISA KEVEPSS 99th pctl

7.8

CVSS v3

NVD

Description

Win32k Elevation of Privilege Vulnerability

CWE-416Use After Free

How to fix

Remediation Available

Windows 10Windows

Install:KB5006675Microsoft

Windows 10 Version 1607Windows

Install:KB5006669Microsoft

Windows 10 Version 1809Windows

Install:KB5006672Microsoft

Windows 10 Version 1909Windows

Install:KB5006667Microsoft

Windows 10 Version 2004Windows

Install:KB5006670Microsoft

Windows 10 Version 20H2Windows

Install:KB5006670Microsoft

Windows 10 Version 21H1Windows

Install:KB5006670Microsoft

Windows 11 version 21H2Windows

Install:KB5006674Microsoft

Windows 7Windows

Install:KB5006743Microsoft

Install:KB5006728Microsoft

Windows 8.1Windows

Install:KB5006729Microsoft

Install:KB5006714Microsoft

Windows RT 8.1Windows

Install:KB5006714Microsoft

Windows Server 2008Windows

Install:KB5006736Microsoft

Install:KB5006715Microsoft

Windows Server 2008 R2Windows

Install:KB5006728Microsoft

Install:KB5006743Microsoft

Windows Server 2012Windows

Install:KB5006739Microsoft

Install:KB5006732Microsoft

Windows Server 2012 (Server Core installation)Windows

Install:KB5006739Microsoft

Install:KB5006732Microsoft

Windows Server 2012 R2Windows

Install:KB5006714Microsoft

Install:KB5006729Microsoft

Windows Server 2012 R2 (Server Core installation)Windows

Install:KB5006729Microsoft

Install:KB5006714Microsoft

Windows Server 2016Windows

Install:KB5006669Microsoft

Windows Server 2016 (Server Core installation)Windows

Install:KB5006669Microsoft

Windows Server 2019Windows

Install:KB5006672Microsoft

Windows Server 2019 (Server Core installation)Windows

Install:KB5006672Microsoft

Windows Server 2022Windows

Install:KB5006699Microsoft

Windows Server 2022 (Server Core installation)Windows

Install:KB5006699Microsoft

Windows Server, version 2004 (Server Core installation)Windows

Install:KB5006670Microsoft

Windows Server, version 20H2 (Server Core Installation)Windows

Install:KB5006670Microsoft

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

73.38%probability of exploitation in 30 days

99thpercentile

Very high risk: more likely to be exploited than 99% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Microsoft Windows Win32k Privilege Escalation Vulnerability

Unspecified vulnerability allows for an authenticated user to escalate privileges.

Apply updates per vendor instructions.

Remediation due: 2021-12-01

Associated with ransomware campaigns

References

Patch1

portal.msrc.microsoft.com

Exploit1

packetstormsecurity.com

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-416 (Use After Free) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2019-0708	Critical	9.8	100%	KEV + Ransom	-
CVE-2021-31166	Critical	9.8	100%	KEV	Fix
CVE-2015-5119	Critical	9.8	99%	KEV	-
CVE-2010-3962	High	8.1	97%	KEV	-
CVE-2015-0313	Critical	9.8	96%	KEV	Fix
CVE-2017-9798	High	7.5	95%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-30.