The SEO Flow by LupsOnline plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the checkBlogAuthentication() and checkCategoryAuthentication() functions in all versions up to, and including, 2.2.1. These authorization functions only implement basic API key authentication but fail to implement WordPress capability checks. This makes it possible for unauthenticated attackers to create, modify, and delete blog posts and categories.