CVE-2026-27124

The record

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 packages

Related vulnerabilities

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• CVE-2026-101905 Axios is a promise-based HTTP client for the browser and Node.js. CWE-441
• CVE-2026-86003 CoreDNS is a DNS server written in Go. CWE-441
• CVE-2026-87582 Confused deputy in DataTransfer in Google Chrome prior to 153.0.8010.36 allowed a remote… CWE-441
• CVE-2026-87502 Confused deputy in Fullscreen in Google Chrome prior to 153.0.8010.36 allowed a remote… CWE-441
• CVE-2026-87453 Confused deputy in BackgroundFetch in Google Chrome prior to 153.0.8010.36 allowed a… CWE-441
• CVE-2026-87442 Confused deputy in Prerender in Google Chrome prior to 153.0.8010.36 allowed a remote… CWE-441
• CVE-2026-86600 In affected Snowflake drivers, WORKLOAD_IDENTITY authentication requests a cloud… CWE-441