The risk manager should first update the risk register with the new risk identified by the vendor. This will help in keeping track of all the risks associated with the project and facilitate the subsequent planning and management of the risks.

 The risk manager should update the new risk in the risk register, which is a project document that records the details of all identified risks, including their description, category, cause, probability, impact, and response strategy. Updating the risk register is the first step to acknowledge the existence of the new risk and to document its characteristics and potential effects on the project objectives. The risk register can then be used as an input for the Plan Risk Responses process, where the risk manager can develop appropriate actions to address the new risk. References: PMI, A Guide to the Project Management Body of Knowledge (PMBOK® Guide), Sixth Edition, 2017, p. 397, 441.