The present business network infrastructure is quickly varying with latest servers, services, connections, and ports added often, at times day by day, and with a uncontrollably inflow of laptops, storage media and wireless networks. With the increasing amount of vulnerabilities and exploits coupled with the recurrent evolution of IT infrastructure, organizations at present require more numerous vulnerability assessments. In this paper new approach the Unified process for Network vulnerability Assessments hereafter called as a unified NVA is proposed for network vulnerability assessment derived from Unified Software Development Process or Unified Process, it is a popular iterative and incremental software development process framework.