CVE-2026-66794

CRITICALPre-NVD 9.39.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 9.3 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-19. A secondary CVSS source baseline 9.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-62598 (ENISA EUVD) · GHSA-9855-9cch-x8mw (GitHub Security Advisories)Source: ENISA EUVD

9.3EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A flaw was found in the cluster-proxy-addon component of Multicluster Engine for Kubernetes. This vulnerability allows an unauthenticated attacker, who can access the user-facing route, to bypass authentication and authorization checks. By manipulating URL path segments, the attacker can proxy requests to arbitrary services across any managed cluster. This enables unauthorized access to internal services that would otherwise be protected, potentially leading to information disclosure or further compromise of the cluster environment.

CVSS v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
57
EG Risk 57/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity93% × 45%
Impact severity (EG Severity): CVSS 9.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
50th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.3): severity, escalated by confirmed exploitation. This CVE's 9.3 is its impact severity (EG Severity), not escalated.

EG Severity
9.3 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-13). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 19, 2026

Last Modified

October 26, 2026

Advisory Details (8)

Auto-updated Oct 3, 2026
Patch available. Sources: redhat.
Red Hat

2507539 – (CVE-2026-66794) CVE-2026-66794 cluster-proxy-addon: cluster-proxy-addon: unauthenticated SSRF to arbitrary managed-cluster services via public Route

https://bugzilla.redhat.com/show_bug.cgi?id=2507539
Red HatMentions a patch (unverified)

CVE-2026-66794 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-66794
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:59593
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:59579
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:59559
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:59558
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:59557
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:59556

Patch Availability(6)

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 22× in last 7d / 92× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 727 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 627 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 17:53 UTCEchelonGraph re-scored
  2. 2026-11-13 17:53 UTCVendor advisory
  3. 2026-11-13 17:53 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  4. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  5. 2026-11-12 19:18 UTCEchelonGraph re-scored
  6. 2026-11-12 19:18 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  7. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  8. 2026-11-11 21:24 UTCEchelonGraph re-scored
  9. 2026-11-11 21:24 UTCVendor advisory
  10. 2026-11-11 21:24 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  11. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  12. 2026-11-10 23:33 UTCEchelonGraph re-scored
  13. 2026-11-10 23:33 UTCVendor advisory
  14. 2026-11-10 23:33 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  15. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  16. 2026-11-10 01:38 UTCEchelonGraph re-scored
  17. 2026-11-10 01:38 UTCVendor advisory
  18. 2026-11-10 01:38 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  19. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  20. 2026-11-09 03:46 UTCEchelonGraph re-scored
  21. 2026-11-09 03:46 UTCVendor advisory
  22. 2026-11-09 03:46 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  23. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  24. 2026-11-08 05:55 UTCEchelonGraph re-scored
  25. 2026-11-08 05:55 UTCVendor advisory
Show 75 more
  1. 2026-11-08 05:55 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  2. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  3. 2026-11-07 08:03 UTCEchelonGraph re-scored
  4. 2026-11-07 08:03 UTCVendor advisory
  5. 2026-11-07 08:03 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  6. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  7. 2026-11-06 10:12 UTCEchelonGraph re-scored
  8. 2026-11-06 10:12 UTCVendor advisory
  9. 2026-11-06 10:12 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  10. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  11. 2026-11-05 12:17 UTCEchelonGraph re-scored
  12. 2026-11-05 12:17 UTCVendor advisory
  13. 2026-11-05 12:17 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  14. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  15. 2026-11-04 14:25 UTCEchelonGraph re-scored
  16. 2026-11-04 14:25 UTCVendor advisory
  17. 2026-11-04 14:25 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  18. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  19. 2026-11-03 16:33 UTCVendor advisory
  20. 2026-11-03 16:33 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  21. 2026-11-02 18:29 UTCEchelonGraph re-scored
  22. 2026-11-02 18:29 UTCVendor advisory
  23. 2026-11-02 18:29 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  24. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  25. 2026-11-01 20:36 UTCEchelonGraph re-scored
  26. 2026-11-01 20:36 UTCVendor advisory
  27. 2026-11-01 20:35 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  28. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  29. 2026-10-31 22:44 UTCEchelonGraph re-scored
  30. 2026-10-31 22:44 UTCVendor advisory
  31. 2026-10-31 22:44 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  32. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  33. 2026-10-31 00:52 UTCEchelonGraph re-scored
  34. 2026-10-31 00:52 UTCVendor advisory
  35. 2026-10-31 00:52 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  36. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  37. 2026-10-30 03:01 UTCEchelonGraph re-scored
  38. 2026-10-30 03:01 UTCVendor advisory
  39. 2026-10-30 03:01 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  40. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  41. 2026-10-29 05:09 UTCEchelonGraph re-scored
  42. 2026-10-29 05:09 UTCVendor advisory
  43. 2026-10-29 05:09 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  44. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  45. 2026-10-28 07:17 UTCEchelonGraph re-scored
  46. 2026-10-28 07:17 UTCVendor advisory
  47. 2026-10-28 07:17 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  48. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  49. 2026-10-27 09:26 UTCEchelonGraph re-scored
  50. 2026-10-27 09:26 UTCVendor advisory
  51. 2026-10-27 09:26 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  52. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  53. 2026-10-26 11:27 UTCVendor advisory
  54. 2026-10-25 16:44 UTCEchelonGraph re-scored
  55. 2026-10-25 16:44 UTCVendor advisory
  56. 2026-10-25 16:44 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  57. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  58. 2026-10-25 14:11 UTCEchelonGraph re-scored
  59. 2026-10-24 18:52 UTCEchelonGraph re-scored
  60. 2026-10-24 18:52 UTCVendor advisory
  61. 2026-10-24 18:52 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  62. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  63. 2026-10-23 21:01 UTCEchelonGraph re-scored
  64. 2026-10-23 21:01 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  65. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  66. 2026-10-22 23:09 UTCEchelonGraph re-scored
  67. 2026-10-22 23:09 UTCVendor advisory
  68. 2026-10-22 23:09 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  69. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  70. 2026-10-22 01:17 UTCEchelonGraph re-scored
  71. 2026-10-22 01:17 UTCVendor advisory
  72. 2026-10-22 01:17 UTCGHSA enrichmentGHSA-9855-9cch-x8mw · GitHub severity CRITICAL · GitHub CVSS 9.3
  73. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  74. 2026-10-21 03:20 UTCEchelonGraph re-scored
  75. 2026-10-21 03:20 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-66794?
CVE-2026-66794 is a critical-severity vulnerability; its CVE record was published on August 19, 2026. A flaw was found in the cluster-proxy-addon component of Multicluster Engine for Kubernetes. This vulnerability allows an unauthenticated attacker, who can access the user-facing route, to bypass authentication and authorization checks. By manipulating URL path segments, the attacker can proxy…
When was CVE-2026-66794 made public?
CVE-2026-66794 was made public on August 19, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on August 19, 2026. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-66794 actively exploited?
CVE-2026-66794 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (50th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66794?
CVE-2026-66794 has a CVSS base score of 9.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-66794?
A fix for CVE-2026-66794 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66794 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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