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Vulnerabilities

Vulnerability · CVE-2021-40449

Microsoft Windows Win32k Privilege Escalation Vulnerability

Published Oct 12, 2021 · catalog updated Jun 16, 2026 · Microsoft Windows

Patch now

CVE-2021-40449 is in the CISA known-exploited catalog, due Dec 1, 2021. Confirm Microsoft Windows against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
High7.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
74.13%
Remediation
Remediation guidance
Affected products
cpe microsoft/windows 10 1507 · cpe microsoft/windows 10 1607 · cpe microsoft/windows 10 1809 · cpe microsoft/windows 10 1909 · cpe microsoft/windows 10 2004 · cpe microsoft/windows 10 20h2

Unspecified vulnerability allows for an authenticated user to escalate privileges.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe microsoft/windows 10 1507version unspecified
  • cpe microsoft/windows 10 1607version unspecified
  • cpe microsoft/windows 10 1809version unspecified
  • cpe microsoft/windows 10 1909version unspecified
  • cpe microsoft/windows 10 2004version unspecified
  • cpe microsoft/windows 10 20h2version unspecified
  • cpe microsoft/windows 10 21h1version unspecified
  • cpe microsoft/windows 11version unspecified
  • vendor Microsoft Windowsversion unspecified

How to fix CVE-2021-40449

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-40449 is in the CISA known-exploited catalog, due Dec 1, 2021. Confirm Microsoft Windows against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply updates per vendor instructions.

What should an analyst verify?

CWE-416: Use After Free. EPSS 74.13%. The CISA KEV listing is the exploitation evidence. A public exploit reference is linked in Sources. That is not the same as confirmed exploitation. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 12, 2021 · Catalog

    Detected

    Unspecified vulnerability allows for an authenticated user to escalate privileges.

  2. Nov 17, 2021 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Dec 1, 2021 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    Unspecified vulnerability allows for an authenticated user to escalate privileges.

Sources

  • CISA KEVConfirmed exploitationCVE-2021-40449

    Unspecified vulnerability allows for an authenticated user to escalate privileges.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2021-40449

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-40449

    30-day exploitation probability 74.1%

    first.org
  • Metasploit ModulesPublic exploit moduleexploit_windows/local/cve_2021_40449

    Public module reference (good). Module source is not copied into this catalog.

    rapid7.com
  • NIST NVDVulnerability recordCVE-2021-40449

    Win32k Elevation of Privilege Vulnerability

    nvd.nist.gov
  • Packet Storm SecurityCited referencehttp://packetstormsecurity.com/files/164926/Win32k-NtGdiResetDC-Use-After-Free-Local-Privilege-Escalation.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • VulnCheck KEVConfirmed exploitationCVE-2021-40449

    Unspecified vulnerability allows for an authenticated user to escalate privileges.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.