An insecure file upload and code execution issue was discovered in Ahsay Cloud Backup Suite 8.3.0.30 via a "PUT /obs/obm7/file/upload" request with the base64-encoded pathname in the X-RSW-custom-encode-path HTTP header, and the content in the HTTP request body. It is possible to upload a file into any directory of the server. One can insert a JSP shell into the web server's directory and execute it. This leads to full system access as the configured user (e.g., Administrator) when starting from any authenticated session (e.g., a trial account). This is fixed in the 83/830122/cbs--hotfix-task26000 builds.