CVE-2026-66364

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-31. A secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 6.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

The GOOSE payload parser contains a boundary handling flaw that can be triggered by a single unauthenticated Layer 2 multicast frame on the process bus. When processing specific payload fields, an attacker controlled inner element length may exceed its enclosing length, causing the parser to over read by one byte. This out-of-bounds read reliably terminates the subscriber process, resulting in a denial-of-service condition.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
29
EG Risk 29/100CISA 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
19th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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

July 30, 2026

Last Modified

September 3, 2026

Advisory Details (2)

Auto-updated Jul 30, 2026
⚠️ Active exploitation confirmed. Patch available. Sources: cisa.
generic

CSAF/csaf_files/OT/white/2026/icsa-26-211-10.json at develop · cisagov/CSAF · GitHub

https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-211-10.json
cisa Patch Available🔴 Active Exploitation

MZ Automation GmbH libiec61850 | CISA

MZ Automation GmbH libiec61850 | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/news-events/ics-advisories/icsa-26-211-10

Vendor Advisories for CVE-2026-66364(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 14× in last 7d / 63× 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 160 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66364?
CVE-2026-66364 is a medium vulnerability published on July 30, 2026. The GOOSE payload parser contains a boundary handling flaw that can be triggered by a single unauthenticated Layer 2 multicast frame on the process bus. When processing specific payload fields, an attacker controlled inner element length may exceed its enclosing length, causing the parser to over…
When was CVE-2026-66364 disclosed?
CVE-2026-66364 was first published on July 30, 2026, with the most recent update on September 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66364 actively exploited?
CVE-2026-66364 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66364?
CVE-2026-66364 has a CVSS base score of 6.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-66364?
A fix for CVE-2026-66364 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66364 are linked in the Vendor Advisories panel on this page.

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