Knowage Server vulnerable to path traversal via upload functionality

Knowage is an open source analytics and business intelligence suite. Starting in the 6.x.x branch and prior to version 8.1.8, the endpoint `/knowage/restful-services/dossier/importTemplateFile` allows authenticated users to upload `template file` on the server, but does not need any authorization to be reached. When the JSP file is uploaded, the attacker just needs to connect to `/knowageqbeengine/foo.jsp` to gain code execution on the server. By exploiting this vulnerability, an attacker with low privileges can upload a JSP file to the `knowageqbeengine` directory and gain code execution capability on the server. This issue has been patched in Knowage version 8.1.8.