Description

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.

INFO

Published Date :

2026-04-03T15:22:17.028Z

Last Modified :

2026-04-03T16:44:20.749Z

Source :

GitHub_M
AFFECTED PRODUCTS

The following products are affected by CVE-2026-27124 vulnerability.

Vendors Products
Jlowin
  • Fastmcp
REFERENCES

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-27124.

URL Resource
https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-rww4-4w9c-7733 cve-icon cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-27124 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-27124 cve-icon
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CVSS Vulnerability Scoring System

Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability
Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact