The WooCommerce Multiple Customer Addresses & Shipping WordPress plugin before 21.7 does not ensure that the address to add/update/retrieve/delete and duplicate belong to the user making the request, or is from a high privilege users, allowing any authenticated users, such as subscriber to add/update/duplicate/delete as well as retrieve addresses of other users.
The WooCommerce Multiple Customer Addresses & Shipping WordPress plugin before 21.7 does not ensure that the address to add/update/retrieve/delete and duplicate belong to the user making the request, or is from a high privilege users, allowing any authenticated users, such as subscriber to add/update/duplicate/delete as well as retrieve addresses of other users.