Security releases issued

Posted by Tim Graham on March 18, 2015

In accordance with our security release policy, the Django team is issuing multiple releases -- Django 1.4.20, 1.6.11, 1.7.7 and 1.8c1. These releases are now available on PyPI and our download page. These releases address several security issues detailed below. We encourage all users of Django to upgrade as soon as possible. The Django master branch has also been updated.

Django 1.8 is now at release candidate stage. This marks the string freeze and the call for translators to submit translations. Provided no major bugs are discovered that can't be solved in the next two weeks, 1.8 final will be issued on or around April 1. Any delays will be communicated on the django-developers mailing list thread.

Denial-of-service possibility with strip_tags()

Last year django.utils.html.strip_tags was changed to work iteratively. The problem is that the size of the input it's processing can increase on each iteration which results in an infinite loop in strip_tags(). This issue only affects versions of Python that haven't received a bugfix in HTMLParser; namely Python < 2.7.7 and 3.3.5. Some operating system vendors have also backported the fix for the Python bug into their packages of earlier versions.

To remedy this issue, strip_tags() will now return the original input if it detects the length of the string it's processing increases. Remember that absolutely NO guarantee is provided about the results of strip_tags() being HTML safe. So NEVER mark safe the result of a strip_tags() call without escaping it first, for example with django.utils.html.escape.

Thanks Andrey Babak for reporting the issue.

This issue has been assigned the identifier CVE-2015-2316.

Mitigated possible XSS attack via user-supplied redirect URLs

Django relies on user input in some cases (e.g. django.contrib.auth.views.login and i18n) to redirect the user to an "on success" URL. The security checks for these redirects (namely django.utils.http.is_safe_url()) accepted URLs with leading control characters and so considered URLs like \x08javascript:... safe. This issue doesn't affect Django currently, since we only put this URL into the Location response header and browsers seem to ignore JavaScript there. Browsers we tested also treat URLs prefixed with control characters such as %08// as relative paths so redirection to an unsafe target isn't a problem either.

However, if a developer relies on is_safe_url() to provide safe redirect targets and puts such a URL into a link, they could suffer from an XSS attack as some browsers such as Google Chrome ignore control characters at the start of a URL in an anchor href.

Thanks Daniel Chatfield for reporting the issue.

This issue has been assigned the identifier CVE-2015-2317.

Affected versions

  • Django master development branch
  • Django 1.8 (currently at release candidate status)
  • Django 1.7
  • Django 1.6
  • Django 1.4 (is_safe_url() issue only)

Per our supported versions policy, Django 1.5 is no longer receiving security updates.


Patches have been applied to Django's master development branch and to the 1.4, 1.6, 1.7, and 1.8 release branches, which resolve the issues described above. The patches may be obtained directly from the following changesets:

On the development master branch:

On the 1.8 release branch:

On the 1.7 release branch:

On the 1.6 release branch:

On the 1.4 release branch:

The following new releases have been issued:

The PGP key ID used for these releases is Tim Graham: 1E8ABDC773EDE252.

General notes regarding security reporting

As always, we ask that potential security issues be reported via private email to, and not via Django's Trac instance or the django-developers list. Please see our security policies for further information.

Back to Top