If you are running this locally, you must expose your server to the internet so the HTB challenge instance can reach it. Using a Reverse Proxy or tools like Serveo is recommended over ngrok for this specific challenge to avoid browser warning screens that might break the automated PDF rendering.
As noted in the official HTB discussion , beginners often overcomplicate this by trying to get a shell, but the goal is purely a file leak. pdfy htb writeup upd
The wkhtmltopdf engine follows the redirect and reads the local file. The content of /etc/passwd is rendered into the PDF. If you are running this locally, you must
This is a known command-line tool that uses the WebKit rendering engine to convert HTML to PDF. Crucially, older versions of this tool are vulnerable to SSRF because they follow redirects and execute JavaScript. The wkhtmltopdf engine follows the redirect and reads