Federal Information Systems Safeguards Act of 2018 This bill provides that the authority of a federal agency to take action to restrict or prohibit access to a website, or to test, deploy, or update a cybersecurity measure, if the agency determines such action is necessary to carry out its responsibilities, shall not be: (1) limited by a collective bargaining agreement or other agreement entered into before, on, or after this bill's enactment pursuant to federal labor-management relations provisions; or (2) negotiated under such provisions.