FreeScout is a free self-hosted help desk and shared mailbox. Versions prior to 1.8.213 have a stored cross-site scripting (XSS) vulnerability in the mailbox si…

FreeScout versions prior to 1.8.213 contain a stored cross-site scripting vulnerability in the mailbox signature feature. The vulnerability stems from incomplete HTML sanitization that only blocks four HTML tags but allows dangerous event handler attributes. Authenticated users with signature permissions can inject arbitrary HTML and JavaScript that executes automatically when agents or administrators view conversations. This enables session hijacking, phishing attacks, email exfiltration, and self-propagating worm behavior across mailboxes. The issue is fixed in version 1.8.213.