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91 lines
4.3 KiB
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91 lines
4.3 KiB
Plaintext
==========================
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Django 1.7.3 release notes
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==========================
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*January 13, 2015*
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Django 1.7.3 fixes several security issues and bugs in 1.7.2.
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WSGI header spoofing via underscore/dash conflation
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===================================================
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When HTTP headers are placed into the WSGI environ, they are normalized by
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converting to uppercase, converting all dashes to underscores, and prepending
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``HTTP_``. For instance, a header ``X-Auth-User`` would become
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``HTTP_X_AUTH_USER`` in the WSGI environ (and thus also in Django's
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``request.META`` dictionary).
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Unfortunately, this means that the WSGI environ cannot distinguish between
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headers containing dashes and headers containing underscores: ``X-Auth-User``
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and ``X-Auth_User`` both become ``HTTP_X_AUTH_USER``. This means that if a
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header is used in a security-sensitive way (for instance, passing
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authentication information along from a front-end proxy), even if the proxy
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carefully strips any incoming value for ``X-Auth-User``, an attacker may be
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able to provide an ``X-Auth_User`` header (with underscore) and bypass this
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protection.
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In order to prevent such attacks, both Nginx and Apache 2.4+ strip all headers
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containing underscores from incoming requests by default. Django's built-in
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development server now does the same. Django's development server is not
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recommended for production use, but matching the behavior of common production
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servers reduces the surface area for behavior changes during deployment.
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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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``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()``) didn't strip leading
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whitespace on the tested URL and as such considered URLs like
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``\njavascript:...`` safe. If a developer relied on ``is_safe_url()`` to
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provide safe redirect targets and put such a URL into a link, they could suffer
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from a XSS attack. This bug doesn't affect Django currently, since we only put
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this URL into the ``Location`` response header and browsers seem to ignore
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JavaScript there.
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Denial-of-service attack against ``django.views.static.serve``
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==============================================================
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In older versions of Django, the :func:`django.views.static.serve` view read
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the files it served one line at a time. Therefore, a big file with no newlines
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would result in memory usage equal to the size of that file. An attacker could
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exploit this and launch a denial-of-service attack by simultaneously requesting
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many large files. This view now reads the file in chunks to prevent large
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memory usage.
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Note, however, that this view has always carried a warning that it is not
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hardened for production use and should be used only as a development aid. Now
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may be a good time to audit your project and serve your files in production
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using a real front-end web server if you are not doing so.
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Database denial-of-service with ``ModelMultipleChoiceField``
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============================================================
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Given a form that uses ``ModelMultipleChoiceField`` and
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``show_hidden_initial=True`` (not a documented API), it was possible for a user
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to cause an unreasonable number of SQL queries by submitting duplicate values
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for the field's data. The validation logic in ``ModelMultipleChoiceField`` now
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deduplicates submitted values to address this issue.
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Bugfixes
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========
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* The default iteration count for the PBKDF2 password hasher has been
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increased by 25%. This part of the normal major release process was
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inadvertently omitted in 1.7. This backwards compatible change will not
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affect users who have subclassed
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``django.contrib.auth.hashers.PBKDF2PasswordHasher`` to change the
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default value.
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* Fixed a crash in the CSRF middleware when handling non-ASCII referer header
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(:ticket:`23815`).
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* Fixed a crash in the ``django.contrib.auth.redirect_to_login`` view when
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passing a ``reverse_lazy()`` result on Python 3 (:ticket:`24097`).
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* Added correct formats for Greek (``el``) (:ticket:`23967`).
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* Fixed a migration crash when unapplying a migration where multiple operations
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interact with the same model (:ticket:`24110`).
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