Django 1.7.3 release notes

    Django 1.7.3 fixes several security issues and bugs in 1.7.2.

    When HTTP headers are placed into the WSGI environ, they are normalized by converting to uppercase, converting all dashes to underscores, and prepending HTTP_. For instance, a header X-Auth-User would become HTTP_X_AUTH_USER in the WSGI environ (and thus also in Django’s request.META dictionary).

    In order to prevent such attacks, both Nginx and Apache 2.4+ strip all headers containing underscores from incoming requests by default. Django’s built-in development server now does the same. Django’s development server is not recommended for production use, but matching the behavior of common production servers reduces the surface area for behavior changes during deployment.

    Django relies on user input in some cases (e.g. django.contrib.auth.views.login() and ) to redirect the user to an “on success” URL. The security checks for these redirects (namely django.utils.http.is_safe_url()) didn’t strip leading whitespace on the tested URL and as such considered URLs like \njavascript:... safe. If a developer relied on is_safe_url() to provide safe redirect targets and put such a URL into a link, they could suffer from a XSS attack. This bug doesn’t affect Django currently, since we only put this URL into the Location response header and browsers seem to ignore JavaScript there.

    Note, however, that this view has always carried a warning that it is not hardened for production use and should be used only as a development aid. Now may be a good time to audit your project and serve your files in production using a real front-end web server if you are not doing so.

    Given a form that uses ModelMultipleChoiceField and show_hidden_initial=True (not a documented API), it was possible for a user to cause an unreasonable number of SQL queries by submitting duplicate values for the field’s data. The validation logic in ModelMultipleChoiceField now deduplicates submitted values to address this issue.

    • Fixed a crash in the CSRF middleware when handling non-ASCII referer header (#23815).
    • Fixed a crash in the django.contrib.auth.redirect_to_login view when passing a result on Python 3 ().
    • Fixed a migration crash when unapplying a migration where multiple operations interact with the same model (#24110).