CVE-2026-66321

CRITICALNVD 9.69.6—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.6 under NVD CVSS v3. EPSS exploit probability: 1.1%, top 38% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
9.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.6Exploit: 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 Edge (Chromium-based) allows an unauthorized attacker to execute code over a network.

CVSS v3
9.6
EG Score
9.6(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity96% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
62%
KEV
Not listed

Published

August 3, 2026

Last Modified

August 20, 2026

Advisory Details (1)

Auto-updated Aug 15, 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-2026-66321

Vendor Advisories for CVE-2026-66321(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.

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 107× in last 7d / 232× 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 232 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-66321?
CVE-2026-66321 is a critical vulnerability published on August 3, 2026. Access of resource using incompatible type ('type confusion') in Microsoft Edge (Chromium-based) allows an unauthorized attacker to execute code over a network.
When was CVE-2026-66321 disclosed?
CVE-2026-66321 was first published in the National Vulnerability Database on August 3, 2026, with the most recent update on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66321 actively exploited?
CVE-2026-66321 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 37.8% of all scored CVEs.
What is the CVSS score of CVE-2026-66321?
CVE-2026-66321 has a CVSS v3 base score of 9.6 (NVD).
How do I remediate CVE-2026-66321?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66321, 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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