DescriptionRuijie NBR series routers contain an unauthenticated arbitrary file upload vulnerability via /ddi/server/fileupload.php. The endpoint accepts attacker-supplied values in the name and uploadDir parameters and saves the provided multipart file content without adequate validation or sanitization of file type, path, or extension. A remote attacker can upload a crafted PHP file and then access it from the web root, resulting in arbitrary code execution in the context of the web service. Exploitation evidence was observed by the Shadowserver Foundation on 2025-01-14 UTC.