CVE-2017-16166: Directory Traversal in byucslabsix

The vulnerability arises from improper path resolution when handling user-supplied URLs. The example exploit uses '/../../../../../../../../../../etc/passwd' in the URL, which suggests the server directly uses req.url to construct filesystem paths. In Node.js, functions like path.join() or fs.readFile() would be involved in this process. If the server does not normalize the resolved path or check if it remains within the intended root directory (e.g., via path.resolve() followed by a startsWith() check), it becomes vulnerable. The PoC's behavior and advisory description align with this pattern, indicating the core request-handling logic is flawed.