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High 8.2
FastMCP: Missing Consent Verification in OAuth Proxy Callback Facilitates Confused Deputy Vulnerabilities
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 tha…
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High 7.4
FastMCP OAuth Proxy token reuse across MCP servers
FastMCP is the standard framework for building MCP applications. Prior to version 2.14.2, the server does not properly respect the resource parameter submitted by the client in the authorization and token request. Instead of issuing the token explicitly for t…
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High —
FastMCP updated to MCP 1.23+ due to CVE-2025-66416
There was a recent CVE report on MCP: https://nvd.nist.gov/vuln/detail/CVE-2025-66416. FastMCP does not use any of the affected components of the MCP SDK directly. However, FastMCP versions prior to 2.14.0 did allow MCP SDK versions <1.23 that were vulnerable…
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High —
FastMCP Auth Integration Allows for Confused Deputy Account Takeover
### Summary FastMCP documentation [covers the scenario](https://gofastmcp.com/integrations/azure) where it is possible to use Entra ID or other providers for authentication. In this context, because Entra ID does not support Dynamic Client Registration (DCR),…