High severityNVD Advisory· Published Mar 16, 2026· Updated Mar 16, 2026
FastMCP OAuth Proxy token reuse across MCP servers
CVE-2025-69196
Description
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 the MCP server, the token is issued for the base_url passed to the OAuthProxy during initialization. This issue has been patched 2.14.2.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fastmcpPyPI | < 2.14.2 | 2.14.2 |
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
3- github.com/advisories/GHSA-5h2m-4q8j-pqpjghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2025-69196ghsaADVISORY
- github.com/PrefectHQ/fastmcp/security/advisories/GHSA-5h2m-4q8j-pqpjghsax_refsource_CONFIRMWEB
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