In the Drupal 7 Term Reference Tree module, two stored XSS vectors exist in the widget/formatter rendering pipeline.
Vector A (token display templates): When the Token module is enabled and token display templates are configured, attacker-controlled token output (e.g., term description) is rendered without proper sanitization. Any user who can edit the referenced taxonomy terms can inject HTML/JS that executes when the field is rendered.
Vector B (term label rendering): Taxonomy term labels are not properly sanitized before being rendered in the widget, allowing a user with permission to create or edit taxonomy terms to inject scripts into the term name that execute when a form containing the widget is viewed.
Exploit affects versions 7.x-1.x up to and including 7.x-1.11.