Rating for update 2.5.1 The rating defines the urgency for installing this update. This release is mandatory for endpoint computers running macOS 10.15 Catalina. Mandatory Mandatory Critical High Priority Recommended Required for all environments. Failure to apply mandatory updates might result in a security breach. Mandatory updates and hotfixes resolve vulnerabilities that might affect product functionality and compromise security. You must apply these updates to maintain a viable and supported product. For more information, see KB51560.