LimeSurvey version prior to 3.14.4 contains a file upload vulnerability in upload functionality that can result in an attacker gaining code execution via webshell. This attack appear to be exploitable via an authenticated user uploading a zip archive which can contains malicious php files that can be called under certain circumstances. This vulnerability appears to have been fixed in after commit 91d143230eb357260a19c8424b3005deb49a47f7 / version 3.14.4.