The primary focus of the present work is to determine the optimal vulnerability patch release time using multi-attribute utility theory (MAUT) by considering two objectives that are cost minimisation and reliability maximisation. The novelty of the study lies in multi-phased research methodology for identifying the attributes affecting the software patch release time through a combination of literature review and the grey-Delphi approach for guiding the optimisation process. The literature has directly considered the weights of the attributes without emphasising their interrelationships, which is overcome by the use of the DEMATEL methodology under the grey environment in the current study for the evaluation of weights of selected attributes. The implications of the study will help in achieving the sustainable development goals pertaining to innovation and infrastructure. A numerical example is used to demonstrate the relevance of the optimisation problem.