CVE-2025-69196 FastMCP OAuth Proxy token reuse across MCP servers
Attackers can reuse OAuth tokens across different MCP servers due to improper resource parameter handling in FastMCP.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-69196?
CVE-2025-69196 is a high-severity authentication bypass vulnerability in jlowin fastmcp, published on 16 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2025-69196?
3 open source packages ship an affected version, including fastmcp. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
fastmcp PyPI | All versions | 2.14.2 |
fastmcp PyPI | All versions | 2.14.2 |
fastmcp PyPI | All versions | 2.14.2 |
Products include Jlowin Fastmcp.
How do I fix CVE-2025-69196?
Upgrade fastmcp to 2.14.2 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2025-69196 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-69196 exists.
Other vulnerabilities in jlowin fastmcp
- CVE-2026-32871 FastMCP OpenAPI Provider has an SSRF & Path Traversal Vulnerability
- CVE-2026-27124 FastMCP: Missing Consent Verification in OAuth Proxy Callback Facilitates Confused Deputy Vulnerabilities
- CVE-2025-64340 FastMCP has a Command Injection vulnerability - Gemini CLI
- CVE-2025-62801 FastMCP vulnerable to windows command injection in FastMCP Cursor installer via server_name
- CVE-2025-62800 FastMCP vulnerable to reflected XSS in client's callback page
Sources
Also known as GHSA-5h2m-4q8j-pqpj, PYSEC-2026-2474, ROOT-APP-PYPI-CVE-2025-69196.