8.2
High
CVE-2026-27124 FastMCP is the standard framework for building MCP applications
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.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| fastmcp 3.2 | earliest → < 3.2.0 | 3.2.0 |
Other CVEs of fastmcp
The 5 CVEs of fastmcp →
CVE-2025-64340
FastMCP is the standard framework for building MCP applications
6.7
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CVE-2025-69196
FastMCP is the standard framework for building MCP applications
7.4
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CVE-2025-62801
FastMCP is the standard framework for building MCP applications
5.4
Medium
CVE-2025-62800
FastMCP is the standard framework for building MCP applications
5.3
Medium