PDF Signer 3.0 Server-Side Template Injection RCE via CSRF Cookie

PDF Signer 3.0 contains a server-side template injection vulnerability that allows unauthenticated attackers to execute arbitrary code by injecting PHP commands through the CSRF-TOKEN cookie parameter. Attackers can craft malicious cookie values containing template injection payloads like shell_exec() to execute system commands and retrieve sensitive information from the server.