FreeScout Vulnerable to Unauthenticated Thread Read-Status Manipulation and Conversation Enumeration via Open Tracking Endpoint

FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.219, the open tracking endpoint `GET /thread/read/{conversation_id}/{thread_id}` allows unauthenticated attackers to enumerate valid conversation and thread IDs, and modify thread state (`opened_at` timestamp) without any authentication. Version 1.8.219 patches the issue.