django-helpdesk < 2.3.3 Stored XSS via HTML Attachments

django-helpdesk before 2.3.3 contains a stored cross-site scripting vulnerability that allows unauthenticated attackers to inject arbitrary JavaScript by submitting HTML-formatted email messages or uploading .html/.htm file attachments through public ticket submission channels. Attackers can exploit the lack of sanitization and Content-Disposition headers at the attachment-serving layer to execute malicious scripts in the browser session of authenticated staff members who open the attachment while triaging tickets.