CVE-2026-27124

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 79% 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, nvd
Elevated
6.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.1Exploit: NoneExposed: 0

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

FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, while testing the GitHubProvider OAuth integration, which allows authentication to a FastMCP MCP server via a FastMCP OAuthProxy using GitHub OAuth, it was discovered that the FastMCP OAuthProxy does not properly validate the user's consent upon receiving the authorization code from GitHub. In combination with GitHub’s behavior of skipping the consent page for previously authorized clients, this introduces a Confused Deputy vulnerability. This issue has been patched in version 3.2.0.

CVSS v3
6.1
EG Score
6.1(medium)
EPSS
11.0%
KEV
Not listed

Published

April 3, 2026

Last Modified

April 22, 2026

References (2)

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
fastmcp0.1.0 ... 3.1.1 (90 versions)3.2.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 50× 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 114 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-27124?
CVE-2026-27124 is a medium vulnerability published on April 3, 2026. FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, while testing the GitHubProvider OAuth integration, which allows authentication to a FastMCP MCP server via a FastMCP OAuthProxy using GitHub OAuth, it was discovered that the FastMCP OAuthProxy does not…
When was CVE-2026-27124 disclosed?
CVE-2026-27124 was first published in the National Vulnerability Database on April 3, 2026, with the most recent update on April 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27124 actively exploited?
CVE-2026-27124 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 11.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-27124?
CVE-2026-27124 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-27124?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27124, 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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