django CMS: Broken access control in page *Duplicate* allows reading the content of any page (cross-site / restriction bypass)

django CMS is an easy-to-use and developer-friendly enterprise content management system powered by Django. Prior to 5.0.9, page duplication lacks an object-level authorization check on the source page. In cms/admin/forms.py, DuplicatePageForm.source accepts any Page, the AddPageForm constructor does not narrow a hidden source field, AddPageForm.clean does not validate the source against the user, and AddPageForm.save calls from_source. In cms/admin/pageadmin.py, duplicate and PageAdmin.has_add_permission check only whether a staff user may add a page. A crafted source value can therefore copy every placeholder and plugin from an unauthorized page with permissions=False, stripping source view restrictions and exposing content across sites or restricted subtrees when CMS_PERMISSION is enabled. This issue is fixed in versions 5.0.9.