Vulnerability Information
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Vulnerability Title
FastMCP OpenAPI Provider has an SSRF & Path Traversal Vulnerability
Vulnerability Description
FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability exists in the _build_url() method. When an OpenAPI operation defines path parameters (e.g., /api/v1/users/{user_id}), the system directly substitutes parameter values into the URL template string without URL-encoding. Subsequently, urllib.parse.urljoin() resolves the final URL. Since urljoin() interprets ../ sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in authenticated SSRF, as requests are sent with the authorization headers configured in the MCP provider. This issue has been patched in version 3.2.0.
CVSS Information
N/A
Vulnerability Type
服务端请求伪造(SSRF)
Vulnerability Title
FastMCP 安全漏洞
Vulnerability Description
FastMCP是Jeremiah Lowin个人开发者的一个MCP服务器构建软件。 FastMCP 3.2.0之前版本存在安全漏洞，该漏洞源于路径参数未进行URL编码，可能导致经过身份验证的服务端请求伪造攻击。
CVSS Information
N/A
Vulnerability Type
N/A