DNN (formerly DotNetNuke) is an open-source web content management platform (CMS) in the Microsoft ecosystem. Prior to 10.1.1, the default HTML editor provider allows unauthenticated file uploads and images can overwrite existing files. An unauthenticated user can upload and replace existing files allowing defacing a website and combined with other issue, injection XSS payloads. This vulnerability is fixed in 10.1.1.