Security vulnerabilities remain a problem for vendors and deployers of software-based systems alike. Vendors play a key role by providing fixes for vulnerabilities, but they have no monopoly on the ability to discover vulnerabilities in their products and services. Knowledge of those vulnerabilities can increase adversarial advantage if deployers are left without recourse to remediate the risks they pose. Coordinated Vulnerability Disclosure (CVD) is the process of gathering information from vulnerability finders, coordinating the sharing of that information between relevant stakeholders, and disclosing the existence of software vulnerabilities and their mitigations to various stakeholders including the public. The CERT Coordination Center has been coordinating the disclosure of software vulnerabilities since its inception in 1988. This document is intended to serve as a guide to those who want to initiate, develop, or improve their own CVD capability. In it, the reader will find an overview of key principles underlying the CVD process, a survey of CVD stakeholders and their roles, and a description of CVD process phases, as well as advice concerning operational considerations and problems that may arise in the provision of CVD and related services.