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44 lines
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44 lines
2.2 KiB
Plaintext
===========================
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Django 1.6.11 release notes
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===========================
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*March 18, 2015*
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Django 1.6.11 fixes two security issues in 1.6.10.
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Denial-of-service possibility with ``strip_tags()``
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===================================================
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Last year :func:`~django.utils.html.strip_tags` was changed to work
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iteratively. The problem is that the size of the input it's processing can
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increase on each iteration which results in an infinite loop in
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``strip_tags()``. This issue only affects versions of Python that haven't
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received `a bugfix in HTMLParser <http://bugs.python.org/issue20288>`_; namely
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Python < 2.7.7 and 3.3.5. Some operating system vendors have also backported
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the fix for the Python bug into their packages of earlier versions.
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To remedy this issue, ``strip_tags()`` will now return the original input if
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it detects the length of the string it's processing increases. Remember that
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absolutely NO guarantee is provided about the results of ``strip_tags()`` being
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HTML safe. So NEVER mark safe the result of a ``strip_tags()`` call without
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escaping it first, for example with :func:`~django.utils.html.escape`.
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Mitigated possible XSS attack via user-supplied redirect URLs
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=============================================================
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Django relies on user input in some cases (e.g.
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:func:`django.contrib.auth.views.login` and :doc:`i18n </topics/i18n/index>`)
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to redirect the user to an "on success" URL. The security checks for these
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redirects (namely ``django.utils.http.is_safe_url()``) accepted URLs with
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leading control characters and so considered URLs like ``\x08javascript:...``
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safe. This issue doesn't affect Django currently, since we only put this URL
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into the ``Location`` response header and browsers seem to ignore JavaScript
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there. Browsers we tested also treat URLs prefixed with control characters such
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as ``%08//example.com`` as relative paths so redirection to an unsafe target
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isn't a problem either.
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However, if a developer relies on ``is_safe_url()`` to
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provide safe redirect targets and puts such a URL into a link, they could
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suffer from an XSS attack as some browsers such as Google Chrome ignore control
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characters at the start of a URL in an anchor ``href``.
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