ClipBucket V5 provides open source video hosting with PHP. Prior to 5.5.1 - 239, a file upload vulnerability exists in the Manage Playlist functionality of the application, specifically surrounding the uploading of playlist cover images. Without proper checks, an attacker can upload a PHP script file instead of an image file, thus allowing a webshell or other malicious files to be stored and executed on the server. This attack vector exists in both the admin area and low-level user area. This vulnerability is fixed in 5.5.1 - 239.
https://github.com/MacWarrior/clipbucket-v5/security/advisories/GHSA-98vm-2xqm-xrcc
https://github.com/MacWarrior/clipbucket-v5/commit/893bfb0f1236c4a59b5e2843ab8d27a1e491b12b