299Ko - Unauthenticated Reflected XSS in Public Contact Form

299Ko's public contact form (plugin/contact/controllers/ContactController.php, home) sets raw POST field values (name, firstname, email, message) into the page template with no sanitization. The template engine's variable output function (common/Template.php, _show_var) echoes values with no htmlspecialchars call, and the sink template (contact.tpl) outputs these values unescaped into an HTML attribute and a textarea.