An unrestricted file upload vulnerability exists in Simple E-Document versions 3.0 to 3.1 that allows an unauthenticated attacker to bypass authentication by sending a specific cookie header (access=3) with HTTP requests. The application’s upload mechanism fails to restrict file types and does not validate or sanitize user-supplied input, allowing attackers to upload malicious .php scripts. Authentication can be bypassed entirely by supplying a specially crafted cookie (access=3), granting access to the upload functionality without valid credentials. If file uploads are enabled on the server, the attacker can upload a web shell and gain remote code execution with the privileges of the web server user, potentially leading to full system compromise.