Requirement changes and cascading effects of change propagation are major sources of inefficiencies in product development and increase the risk of project failure. Risk management regarding these requirement changes yields the potential to handle such changes efficiently. Currently unlocked, a systematic approach is required for risk management to assess the risk of a requirement change with appropriate effort in industrial application. Within the paper at hand, a novel method for systematic assessment of requirement change risk is presented. It is developed in a multiple case study approach with three product development projects from different industrial branches. The change risk is assessed by combining change likelihood and change impact. Propagation effects are considered by analyzing requirement interrelations. To limit application effort, a tailorable approach towards assessment of change causes based on generalized influence factors and a pre-defined rule set for semi-automatized assessment of requirements interrelations is used. A software prototype is developed and implemented to enable evaluation and transfer to industrial application. The approach is evaluated using a combination of case study projects, stakeholder workshops, questionnaires and semi-structured interviews. Applying the method, the risks of requirement changes are assessed systematically, and subsequent risk management is enabled. The contribution at hand opens up the research space of risk management in handling requirement changes which is currently almost unexploited. At the same time, it enables more efficient product development.