CVE-2025-69196

MEDIUM

FastMCP OAuth Proxy token reuse across MCP servers

Title source: cna

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.

References (1)

[X_Refsource_Confirm] https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-5h2m-4q8j-pqpj

Scores

CVSS v3 6.5

EPSS 0.0001

EPSS Percentile 2.7%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Details

CWE

CWE-863

Status published

Products (2)

jlowin/fastmcp < 2.14.2 (2 CPE variants)

pypi/fastmcp 0 - 2.14.2PyPI

Published Mar 16, 2026

Tracked Since Mar 17, 2026