CVE-2026-40366

HIGHPre-NVD 8.48.4—
EchelonGraph scoreMEDIUM confidence

Score 8.4 from GitHub Security Advisory (severity: HIGH) published 2026-05-12. the CNA's CVSS baseline 8.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
8.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.4Exploit: None knownExposed: 0

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

Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.

CVSS v3
8.4
EG Score
8.4(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: 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
Severity84% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

Published

May 12, 2026

Last Modified

August 10, 2026

Advisory Details (1)

Auto-updated May 12, 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-2026-40366

Vendor Advisories for CVE-2026-40366(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 / 76× 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 263 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. 2026-08-23 18:18 UTCEG score recompute
  12. 2026-08-23 18:18 UTCVendor advisory
  13. 2026-08-23 18:18 UTCGHSA enrichment
  14. 2026-08-23 00:19 UTCEPSS rescore
  15. 2026-08-21 23:49 UTCEPSS rescore
  16. 2026-08-20 22:55 UTCEPSS rescore
  17. 2026-08-19 17:03 UTCEPSS rescore
  18. 2026-08-18 13:48 UTCEPSS rescore
  19. 2026-08-17 13:47 UTCEPSS rescore
  20. 2026-08-17 10:51 UTCEG score recompute
  21. 2026-08-17 10:51 UTCVendor advisory
  22. 2026-08-17 10:51 UTCGHSA enrichment
  23. 2026-08-16 14:56 UTCEPSS rescore
  24. 2026-08-16 04:13 UTCEG score recompute
  25. 2026-08-16 04:13 UTCVendor advisory
Show 75 more
  1. 2026-08-16 04:13 UTCGHSA enrichment
  2. 2026-08-16 02:14 UTCEPSS rescore
  3. 2026-08-15 02:19 UTCEG score recompute
  4. 2026-08-15 02:19 UTCVendor advisory
  5. 2026-08-15 02:19 UTCGHSA enrichment
  6. 2026-08-15 01:30 UTCEPSS rescore
  7. 2026-08-14 14:31 UTCVendor advisory
  8. 2026-08-14 14:31 UTCGHSA enrichment
  9. 2026-08-14 02:43 UTCEG score recompute
  10. 2026-08-14 02:43 UTCVendor advisory
  11. 2026-08-14 02:43 UTCGHSA enrichment
  12. 2026-08-13 22:00 UTCEPSS rescore
  13. 2026-08-13 03:59 UTCGHSA enrichment
  14. 2026-08-12 16:11 UTCEG score recompute
  15. 2026-08-12 16:11 UTCVendor advisory
  16. 2026-08-12 16:11 UTCGHSA enrichment
  17. 2026-08-12 13:51 UTCEPSS rescore
  18. 2026-08-11 15:40 UTCEG score recompute
  19. 2026-08-11 15:40 UTCVendor advisory
  20. 2026-08-11 15:40 UTCGHSA enrichment
  21. 2026-08-11 13:43 UTCEPSS rescore
  22. 2026-08-11 03:15 UTCEG score recompute
  23. 2026-08-11 03:15 UTCVendor advisory
  24. 2026-08-11 03:15 UTCGHSA enrichment
  25. 2026-08-11 00:00 UTCEPSS rescore
  26. 2026-08-10 15:28 UTCGHSA enrichment
  27. 2026-08-10 13:36 UTCVendor advisory
  28. 2026-08-10 13:36 UTCGHSA enrichment
  29. 2026-08-10 01:40 UTCVendor advisory
  30. 2026-08-10 01:40 UTCGHSA enrichment
  31. 2026-08-09 13:52 UTCEG score recompute
  32. 2026-08-09 13:52 UTCVendor advisory
  33. 2026-08-09 13:52 UTCGHSA enrichment
  34. 2026-08-09 13:46 UTCEPSS rescore
  35. 2026-08-09 02:04 UTCEG score recompute
  36. 2026-08-09 02:04 UTCVendor advisory
  37. 2026-08-09 02:04 UTCGHSA enrichment
  38. 2026-08-08 16:37 UTCEPSS rescore
  39. 2026-08-08 09:32 UTCVendor advisory
  40. 2026-08-08 09:32 UTCGHSA enrichment
  41. 2026-08-07 21:44 UTCEG score recompute
  42. 2026-08-07 21:44 UTCVendor advisory
  43. 2026-08-07 21:44 UTCGHSA enrichment
  44. 2026-08-07 09:56 UTCVendor advisory
  45. 2026-08-07 09:56 UTCGHSA enrichment
  46. 2026-08-06 21:24 UTCEG score recompute
  47. 2026-08-06 21:24 UTCVendor advisory
  48. 2026-08-06 21:24 UTCGHSA enrichment
  49. 2026-08-06 13:46 UTCEPSS rescore
  50. 2026-08-06 09:36 UTCVendor advisory
  51. 2026-08-06 09:36 UTCGHSA enrichment
  52. 2026-08-05 21:48 UTCEG score recompute
  53. 2026-08-05 21:48 UTCVendor advisory
  54. 2026-08-05 21:48 UTCGHSA enrichment
  55. 2026-08-05 19:17 UTCEPSS rescore
  56. 2026-08-04 15:10 UTCEPSS rescore
  57. 2026-08-04 10:38 UTCEPSS rescore
  58. 2026-08-03 19:15 UTCEG score recompute
  59. 2026-08-03 19:15 UTCVendor advisory
  60. 2026-08-03 19:15 UTCGHSA enrichment
  61. 2026-08-03 10:36 UTCEPSS rescore
  62. 2026-08-02 22:56 UTCVendor advisory
  63. 2026-08-02 22:56 UTCGHSA enrichment
  64. 2026-08-02 11:08 UTCEG score recompute
  65. 2026-08-02 11:08 UTCVendor advisory
  66. 2026-08-02 11:08 UTCGHSA enrichment
  67. 2026-08-02 02:27 UTCEPSS rescore
  68. 2026-08-01 23:14 UTCEG score recompute
  69. 2026-08-01 23:14 UTCVendor advisory
  70. 2026-08-01 23:14 UTCGHSA enrichment
  71. 2026-08-01 04:16 UTCEPSS rescore
  72. 2026-07-30 16:28 UTCEPSS rescore
  73. 2026-07-30 01:30 UTCEPSS rescore
  74. 2026-07-27 14:13 UTCEPSS rescore
  75. 2026-07-26 14:54 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-40366?
CVE-2026-40366 is a high vulnerability published on May 12, 2026. Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
When was CVE-2026-40366 disclosed?
CVE-2026-40366 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-2026-40366 actively exploited?
CVE-2026-40366 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 68.6% of all scored CVEs.
What is the CVSS score of CVE-2026-40366?
CVE-2026-40366 has a CVSS v4.0 base score of 8.4 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-40366?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40366, 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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