CVE-2026-55666

CRITICALPre-NVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 66% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.3Exploit: None knownExposed: 0

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

Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, in apps/meteor/app/apple/server/loginHandler.ts, handleIdentityToken parses a JWT issued by Apple during the OAuth flow. The try block checks for an email parameter. If the JWT does not contain an email address, the application falls back to accepting an arbitrary email value supplied directly in the request. Attackers are able to forge Apple JWTs that do not contain an email address and leverage this vulnerability to carry out account takeover attacks. This vulnerability is fixed in 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
57(Track)
EG Risk 57/100SSVC: 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
Severity93% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

June 24, 2026

Last Modified

June 29, 2026

Advisory Details (1)

Auto-updated Aug 25, 2026
Patch available. Sources: github.
github Patch Available

Email Parameter Fallback Leads To Account Takeover Within Apple OAuth · Advisory · RocketChat/Rocket.Chat · GitHub

https://github.com/RocketChat/Rocket.Chat/security/advisories/GHSA-wx3c-76rf-wpwf

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 52× 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 108 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-55666?
CVE-2026-55666 is a critical vulnerability published on June 24, 2026. Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, in apps/meteor/app/apple/server/loginHandler.ts, handleIdentityToken parses a JWT issued by Apple during the OAuth flow. The try block checks for an…
When was CVE-2026-55666 disclosed?
CVE-2026-55666 was first published in the National Vulnerability Database on June 24, 2026, with the most recent update on June 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55666 actively exploited?
CVE-2026-55666 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 66.4% of all scored CVEs.
What is the CVSS score of CVE-2026-55666?
CVE-2026-55666 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2026-55666?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55666, 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.

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