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51 lines
2.4 KiB
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51 lines
2.4 KiB
Plaintext
==========================
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Django 1.5.3 release notes
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==========================
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*September 10, 2013*
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This is Django 1.5.3, the third release in the Django 1.5 series. It addresses
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one security issue and also contains an opt-in feature to enhance the security
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of :mod:`django.contrib.sessions`.
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Directory traversal vulnerability in ``ssi`` template tag
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=========================================================
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In previous versions of Django it was possible to bypass the
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``ALLOWED_INCLUDE_ROOTS`` setting used for security with the ``ssi``
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template tag by specifying a relative path that starts with one of the allowed
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roots. For example, if ``ALLOWED_INCLUDE_ROOTS = ("/var/www",)`` the following
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would be possible:
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.. code-block:: html+django
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{% ssi "/var/www/../../etc/passwd" %}
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In practice this is not a very common problem, as it would require the template
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author to put the ``ssi`` file in a user-controlled variable, but it's possible
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in principle.
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Mitigating a remote-code execution vulnerability in :mod:`django.contrib.sessions`
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==================================================================================
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:mod:`django.contrib.sessions` currently uses :mod:`pickle` to serialize
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session data before storing it in the backend. If you're using the :ref:`signed
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cookie session backend<cookie-session-backend>` and :setting:`SECRET_KEY` is
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known by an attacker (there isn't an inherent vulnerability in Django that
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would cause it to leak), the attacker could insert a string into their session
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which, when unpickled, executes arbitrary code on the server. The technique for
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doing so is simple and easily available on the internet. Although the cookie
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session storage signs the cookie-stored data to prevent tampering, a
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:setting:`SECRET_KEY` leak immediately escalates to a remote code execution
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vulnerability.
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This attack can be mitigated by serializing session data using JSON rather
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than :mod:`pickle`. To facilitate this, Django 1.5.3 introduces a new setting,
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:setting:`SESSION_SERIALIZER`, to customize the session serialization format.
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For backwards compatibility, this setting defaults to using :mod:`pickle`.
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While JSON serialization does not support all Python objects like :mod:`pickle`
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does, we highly recommend switching to JSON-serialized values. Also,
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as JSON requires string keys, you will likely run into problems if you are
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using non-string keys in ``request.session``. See the
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:ref:`session_serialization` documentation for more details.
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