Wagtail: Improper permission handling when copying pages

Wagtail is an open source content management system built on Django. Prior to 7.0.7, 7.3.2, and 7.4, a CMS user with limited access to pages could copy a page they don't have access to to an area of the site they do. Once coped, they'd be able to view its contents, and potentially publish it. Permissions were correctly checked for the copy destination, but not for the source page. This vulnerability is fixed in 7.0.7, 7.3.2, and 7.4.