Yesterday, the Django team released a security update. The post basically says it all. If you are on Django 1.2.1, UPDATE NOW!
The issue is a standard non-persistent cross site scripting (XSS) exploit. Django explicitly trusted the cross site request forgery token which is supposed to be a hexdigest based on your SECRET_KEY in settings.py. However, cookies are simply stored on the client filesystem and they should generally be considered untrusted user input.
First, setup a simple Django project that has the admin enabled. Visit your simple website and you’ll be issued a CSRF token that is saved in your cookie. Simply edit the token (with Edit this Cookie for Chrome maybe) and enter a script tag and save it. Reload the page and the script tag you entered will get echoed back unescaped and executed.
Edit: I should note that this vulnerability affects any form that uses a CSRF token, not just the admin.