DNN (formerly DotNetNuke) is an open-source web content management platform (CMS) in the Microsoft ecosystem. Prior to version 9.13.9, a malicious SuperUser (Host) could craft a request to use an external url for a site export to then be imported. Version 9.13.9 fixes the issue.
https://github.com/dnnsoftware/Dnn.Platform/security/advisories/GHSA-62mf-vhhw-xmf8
https://github.com/dnnsoftware/Dnn.Platform/commit/13fb13ee76173c3467d7ee8d120b20ca7bd4fa63