CVE-2026-48039: Meta Ads MCP: Unauthenticated HTTP MCP Tool Execution Leaks Operator Meta Access Token

AuthInjectionMiddleware.dispatch() at http_auth_integration.py:272 unconditionally forwards unauthenticated Streamable HTTP requests to downstream MCP tool handlers without issuing a 401 response, allowing any network-reachable caller to invoke MCP tools without authentication. When no per-request credential is present, tool handlers fall back to the META_ACCESS_TOKEN environment variable, and when the downstream Meta Graph API call fails, api.py:263–269 serialises the raw httpx request URL—including the operator’s access_token as a query parameter—into the JSON-RPC response body, delivering the credential to the unauthenticated caller.