CVE-2026-66420

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-31. a secondary CVSS source baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass vulnerability that allows unauthenticated remote attackers to hijack authenticated administrator sessions by exploiting an unconditional early return in the CheckWebServerOriginName() function within webserver.js when self-signed certificates are in use. Attackers can open cross-origin WebSocket connections to any of the twelve WebSocket endpoints, send crafted action commands to exfiltrate the server sessionKey used to sign session cookies, forge session tokens as arbitrary users, and gain full remote control of all managed devices governed by the MeshCentral instance.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

July 30, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Jul 30, 2026
Patch available. Sources: github_pr, github_commit.
generic

MeshCentral Cross-Site WebSocket Hijacking via Origin Validation Bypass on Self-Signed Certificate Deployments | Advisories | VulnCheck

https://www.vulncheck.com/advisories/meshcentral-cross-site-websocket-hijacking-via-origin-validation-bypass-on-self-signed-certificate-deployments
generic

GitHub - Ylianst/MeshCentral: A complete web-based remote monitoring and management web site. Once setup you can install agents and perform remote desktop session to devices on the local network or over the Internet. · GitHub

https://github.com/Ylianst/MeshCentral
github_commit Patch Available

commit f04c9f4 (Ylianst/MeshCentral)

Patch available: Ylianst/MeshCentral 1.2.1 (contains commit f04c9f4)

https://github.com/Ylianst/MeshCentral/commit/f04c9f4
github_pr Patch Available

Fix origin validation for self-signed certificate deployments

Patch available: Ylianst/MeshCentral 1.2.1 (PR #7882 merged 2026-06-08)

https://github.com/Ylianst/MeshCentral/pull/7882

Vendor Advisories for CVE-2026-66420(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 18× in last 7d / 91× 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 185 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-66420?
CVE-2026-66420 is a high vulnerability published on July 30, 2026. MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass vulnerability that allows unauthenticated remote attackers to hijack authenticated administrator sessions by exploiting an unconditional early return in the CheckWebServerOriginName() function within webserver.js when…
When was CVE-2026-66420 disclosed?
CVE-2026-66420 was first published in the National Vulnerability Database on July 30, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66420 actively exploited?
CVE-2026-66420 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 93.8% of all scored CVEs.
What is the CVSS score of CVE-2026-66420?
CVE-2026-66420 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-66420?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66420, 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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