"AuthInjectionMiddleware" in "meta-ads-mcp" rejects HTTP MCP requests only when both "auth_token" and "pipeboard_token" are absent. Because "extract_token_from_headers()" does not recognise the "X-Pipeboard-Token" header, an attacker who sends that header with any arbitrary value produces "auth_token = None" and "pipeboard_token = <attacker value>", making the guard condition evaluate to "False" and passing the request through. No authentication context is set; the token getter falls back to the server operator's "META_ACCESS_TOKEN" environment variable. Every subsequent MCP tool call executes with the operator's Meta credentials, allowing an unauthenticated network caller to read and write the operator's Meta Ads data.