CVE-2021-40450: Technical Deep-Dive (Auto Refreshed)

Generated on 2026-03-30T13:25:42.271Z. This file is automatically regenerated every 30 minutes by the CVE AI enrichment job using web sources (NVD, MITRE, CISA KEV, GitHub).

Executive Technical Summary

Win32k Elevation of Privilege Vulnerability

• Context preserved from previous revision: Win32k Elevation of Privilege Vulnerability Notes: Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.

Technical Details

• CVE: CVE-2021-40450
• KEV date added: 2022-04-25
• KEV due date: 2022-05-16
• NVD published: 2021-10-13
• NVD modified: 2025-10-30
• MITRE modified: 2025-10-21
• CVSS base score: 7.8
• CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• CVSS exploitability score: 1.8
• CVSS impact score: 5.9
• Attack vector: Local
• Attack complexity: Low
• Privileges required: Low
• User interaction: None
• Scope: Unchanged
• Confidentiality impact: High
• Integrity impact: High
• Availability impact: High

Versions and Products Impacted

• microsoft / windows 10 1809 (versions: < 10.0.17763.2237)
• microsoft / windows 10 1909 (versions: < 10.0.18363.1854)
• microsoft / windows 10 2004 (versions: < 10.0.19041.1288)
• microsoft / windows 10 20h2 (versions: < 10.0.19042.1288)
• microsoft / windows 10 21h1 (versions: < 10.0.19043.1288)
• microsoft / windows 11 21h2 (versions: < 10.0.22000.258)
• microsoft / windows server 2004 (versions: < 10.0.19041.1288)
• microsoft / windows server 2019 (versions: < 10.0.17763.2237)
• microsoft / windows server 2022 (versions: < 10.0.20348.288)
• microsoft / windows server 20h2 (versions: < 10.0.19042.1288)
• Microsoft / Windows 10 Version 1809 (versions: 10.0.0)
• Microsoft / Windows Server 2019 (versions: 10.0.0)
• Microsoft / Windows Server 2019 (Server Core installation) (versions: 10.0.0)
• Microsoft / Windows 10 Version 1909 (versions: 10.0.0)
• Microsoft / Windows 10 Version 21H1 (versions: 10.0.0)
• Microsoft / Windows Server 2022 (versions: 10.0.0)
• Microsoft / Windows 10 Version 2004 (versions: 10.0.0)
• Microsoft / Windows Server version 2004 (versions: 10.0.0)
• Microsoft / Windows 10 Version 20H2 (versions: 10.0.0)
• Microsoft / Windows Server version 20H2 (versions: 10.0.0)

Weakness Classification

• NVD-CWE-noinfo
• CWE-noinfo Not enough information

Repositories for Lab Validation (Public Examples)

• Ostorlab/KEV | stars: 608 | updated: 2026-03-23 | https://github.com/Ostorlab/KEV
  Notes: Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.
• ycdxsb/WindowsPrivilegeEscalation | stars: 471 | updated: 2026-03-28 | https://github.com/ycdxsb/WindowsPrivilegeEscalation
  Notes: Collection of Windows Privilege Escalation (Analyse/PoC/Exploit)
• andraxsnakesecurity/CVE-PoC-in-GitHub | stars: 13 | updated: 2026-01-16 | https://github.com/andraxsnakesecurity/CVE-PoC-in-GitHub
  Notes: All CVE - PoC in GitHub
• zecool/cve | stars: 2 | updated: 2025-06-24 | https://github.com/zecool/cve

People and Organizations Mentioned

• microsoft
• Win32k
• Ostorlab
• ycdxsb
• andraxsnakesecurity
• zecool

Practical Defensive Validation (Authorized Only)

1. Use only isolated environments and systems you own or are explicitly authorized to test.
2. Snapshot infrastructure before validation and preserve baseline logs (EDR, SIEM, OS, app).
3. Create low-privilege users on microsoft / windows 10 1809 (versions: < 10.0.17763.2237) and validate that patching blocks unauthorized admin-level actions.
4. Compare token/privilege transitions in Windows Event Logs before and after remediation.
5. Tune detections for unusual group membership changes and SYSTEM-level process launches from user sessions.

References

• NVD record: https://nvd.nist.gov/vuln/detail/CVE-2021-40450
• MITRE CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40450
• CISA KEV Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• CISA KEV JSON feed: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
• KEV notes: https://nvd.nist.gov/vuln/detail/CVE-2021-40450
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40450
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40450
• Repository example: https://github.com/Ostorlab/KEV
• Repository example: https://github.com/ycdxsb/WindowsPrivilegeEscalation
• Repository example: https://github.com/andraxsnakesecurity/CVE-PoC-in-GitHub
• Repository example: https://github.com/zecool/cve

This content is for defensive security training and authorized validation only.