CVE-2021-40450

CRITICALNVD 7.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2022-04-25), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 7.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 2%CVSS: 7.8Exploit: cisa kev · ssvc activeExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Win32k Elevation of Privilege Vulnerability

CVSS v3
7.8
EG Score
9.0(high)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
2%
EPSS %ILE
78%
KEV
⚠ Exploited

Published

October 13, 2021

Last Modified

October 30, 2025

Advisory Details (2)

Auto-updated Jun 3, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: microsoft, cisa.
cisa Patch Available🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40450
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

Security Update Guide - Microsoft Security Response Center. Patch available via Microsoft Security Update

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

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 66× in last 7d / 404× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 835 total refreshes for this CVE.

  1. 2026-07-29 16:20 UTCVendor advisory
  2. 2026-07-29 16:20 UTCGHSA enrichment
  3. 2026-07-29 12:35 UTCVendor advisory
  4. 2026-07-29 12:35 UTCGHSA enrichment
  5. 2026-07-29 08:50 UTCVendor advisory
  6. 2026-07-29 08:50 UTCGHSA enrichment
  7. 2026-07-29 05:06 UTCVendor advisory
  8. 2026-07-29 05:06 UTCGHSA enrichment
  9. 2026-07-29 01:22 UTCVendor advisory
  10. 2026-07-29 01:22 UTCGHSA enrichment
  11. 2026-07-28 21:38 UTCVendor advisory
  12. 2026-07-28 21:38 UTCGHSA enrichment
  13. 2026-07-28 17:54 UTCEG score recompute
  14. 2026-07-28 17:54 UTCVendor advisory
  15. 2026-07-28 17:54 UTCGHSA enrichment
  16. 2026-07-28 15:33 UTCEPSS rescore
  17. 2026-07-28 14:10 UTCVendor advisory
  18. 2026-07-28 14:10 UTCGHSA enrichment
  19. 2026-07-28 10:24 UTCVendor advisory
  20. 2026-07-28 10:23 UTCGHSA enrichment
  21. 2026-07-28 06:36 UTCVendor advisory
  22. 2026-07-28 06:36 UTCGHSA enrichment
  23. 2026-07-28 02:52 UTCVendor advisory
  24. 2026-07-28 02:52 UTCGHSA enrichment
  25. 2026-07-27 23:08 UTCVendor advisory
Show 75 more
  1. 2026-07-27 23:07 UTCGHSA enrichment
  2. 2026-07-27 19:24 UTCCISA KEV update
  3. 2026-07-27 19:20 UTCVendor advisory
  4. 2026-07-27 19:20 UTCGHSA enrichment
  5. 2026-07-27 17:17 UTCCISA KEV update
  6. 2026-07-27 15:35 UTCEG score recompute
  7. 2026-07-27 15:35 UTCVendor advisory
  8. 2026-07-27 15:35 UTCGHSA enrichment
  9. 2026-07-27 11:51 UTCGHSA enrichment
  10. 2026-07-27 08:07 UTCVendor advisory
  11. 2026-07-27 08:07 UTCGHSA enrichment
  12. 2026-07-27 04:23 UTCVendor advisory
  13. 2026-07-27 04:22 UTCGHSA enrichment
  14. 2026-07-27 00:36 UTCVendor advisory
  15. 2026-07-27 00:36 UTCGHSA enrichment
  16. 2026-07-26 20:51 UTCVendor advisory
  17. 2026-07-26 20:51 UTCGHSA enrichment
  18. 2026-07-26 17:04 UTCEG score recompute
  19. 2026-07-26 17:04 UTCVendor advisory
  20. 2026-07-26 17:04 UTCGHSA enrichment
  21. 2026-07-26 14:52 UTCEPSS rescore
  22. 2026-07-26 14:52 UTCEPSS rescore
  23. 2026-07-26 13:18 UTCEG score recompute
  24. 2026-07-26 13:18 UTCVendor advisory
  25. 2026-07-26 13:18 UTCGHSA enrichment
  26. 2026-07-26 09:33 UTCVendor advisory
  27. 2026-07-26 09:33 UTCGHSA enrichment
  28. 2026-07-26 05:48 UTCVendor advisory
  29. 2026-07-26 05:48 UTCGHSA enrichment
  30. 2026-07-26 02:03 UTCEG score recompute
  31. 2026-07-26 02:03 UTCVendor advisory
  32. 2026-07-26 02:03 UTCGHSA enrichment
  33. 2026-07-25 14:15 UTCEPSS rescore
  34. 2026-07-24 14:15 UTCEPSS rescore
  35. 2026-07-23 14:16 UTCEPSS rescore
  36. 2026-07-23 02:04 UTCEG score recompute
  37. 2026-07-22 22:27 UTCEG score recompute
  38. 2026-07-22 22:27 UTCVendor advisory
  39. 2026-07-22 22:27 UTCGHSA enrichment
  40. 2026-07-22 19:40 UTCCISA KEV update
  41. 2026-07-22 18:41 UTCGHSA enrichment
  42. 2026-07-22 14:55 UTCEG score recompute
  43. 2026-07-22 14:55 UTCVendor advisory
  44. 2026-07-22 14:55 UTCGHSA enrichment
  45. 2026-07-22 14:06 UTCEPSS rescore
  46. 2026-07-22 11:11 UTCVendor advisory
  47. 2026-07-22 11:11 UTCGHSA enrichment
  48. 2026-07-22 07:27 UTCVendor advisory
  49. 2026-07-22 07:27 UTCGHSA enrichment
  50. 2026-07-22 03:42 UTCVendor advisory
  51. 2026-07-22 03:42 UTCGHSA enrichment
  52. 2026-07-21 23:57 UTCVendor advisory
  53. 2026-07-21 23:57 UTCGHSA enrichment
  54. 2026-07-21 20:07 UTCVendor advisory
  55. 2026-07-21 20:07 UTCGHSA enrichment
  56. 2026-07-21 16:22 UTCEG score recompute
  57. 2026-07-21 16:22 UTCVendor advisory
  58. 2026-07-21 16:22 UTCGHSA enrichment
  59. 2026-07-21 15:22 UTCEPSS rescore
  60. 2026-07-21 15:22 UTCEPSS rescore
  61. 2026-07-21 14:37 UTCCISA KEV update
  62. 2026-07-21 12:39 UTCVendor advisory
  63. 2026-07-21 12:39 UTCGHSA enrichment
  64. 2026-07-21 08:55 UTCVendor advisory
  65. 2026-07-21 08:55 UTCGHSA enrichment
  66. 2026-07-21 05:11 UTCVendor advisory
  67. 2026-07-21 05:11 UTCGHSA enrichment
  68. 2026-07-21 01:26 UTCVendor advisory
  69. 2026-07-21 01:26 UTCGHSA enrichment
  70. 2026-07-20 21:42 UTCVendor advisory
  71. 2026-07-20 21:42 UTCGHSA enrichment
  72. 2026-07-20 17:58 UTCEG score recompute
  73. 2026-07-20 17:58 UTCVendor advisory
  74. 2026-07-20 17:58 UTCGHSA enrichment
  75. 2026-07-20 17:05 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(6)

What is CVE-2021-40450?
CVE-2021-40450 is a critical vulnerability published on October 13, 2021. Win32k Elevation of Privilege Vulnerability
When was CVE-2021-40450 disclosed?
CVE-2021-40450 was first published in the National Vulnerability Database on October 13, 2021, with the most recent update on October 30, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-40450 actively exploited?
Yes. CISA added CVE-2021-40450 to the Known Exploited Vulnerabilities catalog on April 25, 2022, affecting Microsoft Win32k. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2021-40450?
CVE-2021-40450 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.
Which products are affected by CVE-2021-40450?
CVE-2021-40450 affects Microsoft Win32k. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2021-40450?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40450, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2021-40450

Explore →

Is Your Infrastructure Affected by CVE-2021-40450?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs