In Octopus Deploy 2019.1.0 through 2019.3.1 and 2019.4.0 through 2019.4.5, an authenticated user with the VariableViewUnscoped or VariableEditUnscoped permission scoped to a specific project could view or edit unscoped variables from a different project. (These permissions are only used in custom User Roles and do not affect built in User Roles.)
In Octopus Deploy 2019.4.0 through 2019.6.x before 2019.6.6, and 2019.7.x before 2019.7.6, an authenticated system administrator is able to view sensitive values by visiting a server configuration page or making an API call.