Zammad: Missing authorization on ticket attachment download

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2, a customer who can view a ticket cannot see internal ticket articles through the article listing API. However, the same customer can directly request an attachment belonging to an internal article via the attachment download endpoint, bypassing article-level authorization. This results in an inconsistency: The article listing hides internal articles from customers. The attachment download only checks the parent ticket, not the article, so the same customer can download the attachment directly. This issue is fixed in version 7.0.2.