CVE-2026-66318

HIGHPre-NVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-08-04. The CNA's CVSS baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:microsoft, epss, ghsa
Trending — 4 sources updated this week
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 8.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Origin validation error in Microsoft Edge (Chromium-based) allows an unauthorized attacker to disclose information over a network.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
37
EG Risk 37/100CISA SSVC

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
Severity81% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
27th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 3, 2026

Last Modified

September 25, 2026

Advisory Details (1)

Auto-updated Aug 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-2026-66318

Vendor Advisories for CVE-2026-66318(2)

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 26× in last 7d / 133× 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 350 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66318?
CVE-2026-66318 is a high vulnerability published on August 3, 2026. Origin validation error in Microsoft Edge (Chromium-based) allows an unauthorized attacker to disclose information over a network.
When was CVE-2026-66318 disclosed?
CVE-2026-66318 was first published on August 3, 2026, with the most recent update on September 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66318 actively exploited?
CVE-2026-66318 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (27th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66318?
CVE-2026-66318 has a CVSS base score of 8.1 (the CNA's own assessment, by microsoft; NVD's own analysis pending).
How do I remediate CVE-2026-66318?
A fix for CVE-2026-66318 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66318 are linked in the Vendor Advisories panel on this page.

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