FastMCP <=2.14.2: OAuthProxy Issues Token for Base_URL Instead of Server
CVE-2025-69196 Published on March 16, 2026
FastMCP OAuth Proxy token reuse across MCP servers
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.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2025-69196 has been classified to as an AuthZ vulnerability or weakness.
Affected Versions
jlowin fastmcp Version < 2.14.2 is affected by CVE-2025-69196Vulnerable Packages
The following package name and versions may be associated with CVE-2025-69196
| Package Manager | Vulnerable Package | Versions | Fixed In |
|---|---|---|---|
| pip | fastmcp | < 2.14.2 | 2.14.2 |
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.