Bug 2454826 (CVE-2026-27124) - CVE-2026-27124 FastMCP: FastMCP OAuthProxy: FastMCP OAuthProxy: Unauthorized actions due to improper consent validation in GitHub OAuth
Summary: CVE-2026-27124 FastMCP: FastMCP OAuthProxy: FastMCP OAuthProxy: Unauthorized ...
Keywords:
Status: NEW
Alias: CVE-2026-27124
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-04-03 16:02 UTC by OSIDB Bzimport
Modified: 2026-04-06 18:26 UTC (History)
28 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-04-03 16:02:53 UTC 
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.
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