CVE-2026-40402

CRITICALPre-NVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

Score 9.3 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-12. the CNA's CVSS baseline 9.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.3Exploit: None knownExposed: 0

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

Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
42(Track)
EG Risk 42/100SSVC: Track

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
Severity93% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
26%
KEV
Not listed

Published

May 12, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated Sep 3, 2026
Patch available. Sources: microsoft.
microsoft Patch Available

Security Update Guide - Microsoft Security Response Center

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

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402

Vendor Advisories for CVE-2026-40402(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 118× 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 431 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-40402?
CVE-2026-40402 is a critical vulnerability published on May 12, 2026. Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.
When was CVE-2026-40402 disclosed?
CVE-2026-40402 was first published in the National Vulnerability Database on May 12, 2026, with the most recent update on August 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40402 actively exploited?
CVE-2026-40402 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 74.1% of all scored CVEs.
What is the CVSS score of CVE-2026-40402?
CVE-2026-40402 has a CVSS v4.0 base score of 9.3 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-40402?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40402, 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

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