REDAXO is a PHP-based CMS. In Redaxo before 5.18.3, the mediapool/media page is vulnerable to arbitrary file upload. This vulnerability is fixed in 5.18.3.
https://github.com/redaxo/redaxo/security/advisories/GHSA-wppf-gqj5-fc4f
https://github.com/redaxo/redaxo/commit/3b2159bb45da0ab6cfaef5c8cf8b602ee5e2fb37