Critical Vulnerability Information Vulnerability Type SSRF (Server-Side Request Forgery) Vulnerability Description The research page intentionally exposes an SSRF vulnerability, allowing attackers to submit unexpected and parameters. The tutorial demonstrates how to exploit this to make the server connect to a website controlled by the attacker. Additionally, there is a vulnerability in where, if the target URL request fails, it causes the server to crash. Vulnerability Example When accessing while the server is running on local port 4000, a crash occurs. Error Message Root Cause Analysis The needle callback skips setting when an error occurs, but still attempts to append to . If an error occurs, is undefined, causing the server to crash. Solution A check should be added to handle the case where is undefined. A PR to fix this issue was submitted and merged.