CVE-2026-66720

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 subscriber component improperly validates the UTC timestamp field in unauthenticated IEC 61850 GOOSE (EtherType 0x88B8) Layer-2 multicast messages. A specially crafted GOOSE frame containing an undersized timestamp field can trigger a heap out-of-bounds read during message processing, causing the process to crash and 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.
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
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

Vendor Advisories for CVE-2026-66720(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 / 64× 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 164 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 13:52 UTCEPSS rescore
  15. 2026-09-27 18:58 UTCEG score recompute
  16. 2026-09-27 18:58 UTCGHSA enrichment
  17. 2026-09-27 13:48 UTCEPSS rescore
  18. 2026-09-26 15:59 UTCEPSS rescore
  19. 2026-09-25 04:55 UTCEG score recompute
  20. 2026-09-25 04:55 UTCGHSA enrichment
  21. 2026-09-23 21:27 UTCEG score recompute
  22. 2026-09-23 21:27 UTCGHSA enrichment
  23. 2026-09-23 17:54 UTCEPSS rescore
  24. 2026-09-22 15:11 UTCEG score recompute
  25. 2026-09-22 15:11 UTCGHSA enrichment
Show 75 more
  1. 2026-09-20 20:16 UTCEPSS rescore
  2. 2026-09-19 23:45 UTCEG score recompute
  3. 2026-09-19 23:45 UTCGHSA enrichment
  4. 2026-09-19 00:37 UTCEG score recompute
  5. 2026-09-19 00:37 UTCGHSA enrichment
  6. 2026-09-18 19:28 UTCEPSS rescore
  7. 2026-09-18 02:13 UTCEG score recompute
  8. 2026-09-18 02:13 UTCGHSA enrichment
  9. 2026-09-17 03:54 UTCEG score recompute
  10. 2026-09-17 03:54 UTCGHSA enrichment
  11. 2026-09-16 14:08 UTCEPSS rescore
  12. 2026-09-16 05:31 UTCEG score recompute
  13. 2026-09-16 05:31 UTCGHSA enrichment
  14. 2026-09-16 05:15 UTCEPSS rescore
  15. 2026-09-15 03:12 UTCEG score recompute
  16. 2026-09-15 03:12 UTCGHSA enrichment
  17. 2026-09-13 23:55 UTCEG score recompute
  18. 2026-09-13 23:55 UTCGHSA enrichment
  19. 2026-09-13 01:36 UTCEG score recompute
  20. 2026-09-13 01:36 UTCGHSA enrichment
  21. 2026-09-12 03:15 UTCEG score recompute
  22. 2026-09-12 03:15 UTCGHSA enrichment
  23. 2026-09-11 14:53 UTCEPSS rescore
  24. 2026-09-11 09:37 UTCEPSS rescore
  25. 2026-09-11 04:53 UTCEG score recompute
  26. 2026-09-11 04:53 UTCGHSA enrichment
  27. 2026-09-10 05:43 UTCGHSA enrichment
  28. 2026-09-09 07:09 UTCEG score recompute
  29. 2026-09-09 07:09 UTCGHSA enrichment
  30. 2026-09-08 22:01 UTCEPSS rescore
  31. 2026-09-07 19:43 UTCEG score recompute
  32. 2026-09-07 19:43 UTCGHSA enrichment
  33. 2026-09-07 16:01 UTCEPSS rescore
  34. 2026-09-06 17:20 UTCEG score recompute
  35. 2026-09-06 17:20 UTCGHSA enrichment
  36. 2026-09-06 13:47 UTCEPSS rescore
  37. 2026-09-05 18:48 UTCEG score recompute
  38. 2026-09-05 18:48 UTCGHSA enrichment
  39. 2026-09-05 15:31 UTCEPSS rescore
  40. 2026-09-04 16:58 UTCEG score recompute
  41. 2026-09-04 16:58 UTCGHSA enrichment
  42. 2026-09-04 05:07 UTCEPSS rescore
  43. 2026-09-03 18:25 UTCEG score recompute
  44. 2026-09-03 18:25 UTCGHSA enrichment
  45. 2026-09-02 14:12 UTCEPSS rescore
  46. 2026-09-01 22:36 UTCEG score recompute
  47. 2026-09-01 22:36 UTCGHSA enrichment
  48. 2026-09-01 13:54 UTCEPSS rescore
  49. 2026-09-01 04:40 UTCEPSS rescore
  50. 2026-08-31 23:29 UTCGHSA enrichment
  51. 2026-08-30 20:46 UTCEG score recompute
  52. 2026-08-30 20:46 UTCGHSA enrichment
  53. 2026-08-30 19:17 UTCEPSS rescore
  54. 2026-08-30 01:22 UTCEPSS rescore
  55. 2026-08-29 22:28 UTCEG score recompute
  56. 2026-08-29 22:27 UTCGHSA enrichment
  57. 2026-08-28 21:42 UTCEPSS rescore
  58. 2026-08-27 20:47 UTCEG score recompute
  59. 2026-08-27 20:47 UTCGHSA enrichment
  60. 2026-08-26 19:16 UTCEG score recompute
  61. 2026-08-26 19:16 UTCGHSA enrichment
  62. 2026-08-26 14:47 UTCEPSS rescore
  63. 2026-08-25 19:58 UTCEG score recompute
  64. 2026-08-25 19:58 UTCGHSA enrichment
  65. 2026-08-25 13:49 UTCEPSS rescore
  66. 2026-08-24 21:40 UTCEG score recompute
  67. 2026-08-24 21:40 UTCGHSA enrichment
  68. 2026-08-23 22:55 UTCEG score recompute
  69. 2026-08-23 22:55 UTCGHSA enrichment
  70. 2026-08-23 00:19 UTCEPSS rescore
  71. 2026-08-23 00:17 UTCGHSA enrichment
  72. 2026-08-22 01:58 UTCEG score recompute
  73. 2026-08-22 01:58 UTCGHSA enrichment
  74. 2026-08-21 23:49 UTCEPSS rescore
  75. 2026-08-21 03:39 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66720?
CVE-2026-66720 is a medium vulnerability published on July 30, 2026. The GOOSE subscriber component improperly validates the UTC timestamp field in unauthenticated IEC 61850 GOOSE (EtherType 0x88B8) Layer-2 multicast messages. A specially crafted GOOSE frame containing an undersized timestamp field can trigger a heap out-of-bounds read during message processing,…
When was CVE-2026-66720 disclosed?
CVE-2026-66720 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-2026-66720 actively exploited?
CVE-2026-66720 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-2026-66720?
CVE-2026-66720 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-2026-66720?
A fix for CVE-2026-66720 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66720 are linked in the Vendor Advisories panel on this page.

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