55 lines
2.7 KiB
Plaintext
55 lines
2.7 KiB
Plaintext
===========================
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Django 1.4.21 release notes
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===========================
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*July 8, 2015*
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Django 1.4.21 fixes several security issues in 1.4.20.
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Denial-of-service possibility by filling session store
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======================================================
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In previous versions of Django, the session backends created a new empty record
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in the session storage anytime ``request.session`` was accessed and there was a
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session key provided in the request cookies that didn't already have a session
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record. This could allow an attacker to easily create many new session records
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simply by sending repeated requests with unknown session keys, potentially
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filling up the session store or causing other users' session records to be
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evicted.
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The built-in session backends now create a session record only if the session
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is actually modified; empty session records are not created. Thus this
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potential DoS is now only possible if the site chooses to expose a
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session-modifying view to anonymous users.
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As each built-in session backend was fixed separately (rather than a fix in the
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core sessions framework), maintainers of third-party session backends should
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check whether the same vulnerability is present in their backend and correct
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it if so.
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Header injection possibility since validators accept newlines in input
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======================================================================
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Some of Django's built-in validators
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(:class:`~django.core.validators.EmailValidator`, most seriously) didn't
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prohibit newline characters (due to the usage of ``$`` instead of ``\Z`` in the
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regular expressions). If you use values with newlines in HTTP response or email
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headers, you can suffer from header injection attacks. Django itself isn't
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vulnerable because :class:`~django.http.HttpResponse` and the mail sending
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utilities in :mod:`django.core.mail` prohibit newlines in HTTP and SMTP
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headers, respectively. While the validators have been fixed in Django, if
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you're creating HTTP responses or email messages in other ways, it's a good
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idea to ensure that those methods prohibit newlines as well. You might also
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want to validate that any existing data in your application doesn't contain
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unexpected newlines.
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:func:`~django.core.validators.validate_ipv4_address`,
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:func:`~django.core.validators.validate_slug`, and
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:class:`~django.core.validators.URLValidator` and their usage in the
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corresponding form fields ``GenericIPAddresseField``, ``IPAddressField``,
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``SlugField``, and ``URLField`` are also affected.
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The undocumented, internally unused ``validate_integer()`` function is now
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stricter as it validates using a regular expression instead of simply casting
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the value using ``int()`` and checking if an exception was raised.
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