FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to 1.8.212, the endpoint GET /thread/read/{conversation_id}/{thread_id} does not require authentication and does not validate whether the given thread_id belongs to the given conversation_id. This allows any unauthenticated attacker to mark any thread as read by passing arbitrary IDs, enumerate valid thread IDs via HTTP response codes (200 vs 404), and manipulate opened_at timestamps across conversations (IDOR). This vulnerability is fixed in 1.8.212.