FreeScout Stored XSS vulnerability in mailbox auto-reply: payload reaches every customer's email client (no CSP), bypassing strip_tags validator with mixed text+HTML content

FreeScout is a free help desk and shared inbox built with PHP's Laravel framework. Prior to version 1.8.217, a user with updateAutoReply permission can store an XSS payload in the mailbox auto-reply message. The payload is rendered unescaped in the auto-reply email sent to every customer who contacts the mailbox. Email clients do not enforce CSP, so the payload executes in the customer's webmail / mail-client context. This issue has been patched in version 1.8.217.