An unrestricted upload of files with a dangerous type in the thumbnail-upload endpoint (/index.php?m=member&f=article&v=thumbUpload) of WuzhiCMS 5.0.0 allows an authenticated low-privileged member to upload a crafted .php file and execute arbitrary PHP code on the server, because the stored file extension is taken verbatim from the client-supplied filename with no extension allowlist or content validation and the file is written to the web-accessible uploadfile/ directory, from which the web server executes PHP.