===========================

Django 1.4.14 release notes

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*August 20, 2014*

Django 1.4.14 fixes several security issues in 1.4.13.

``reverse()`` could generate URLs pointing to other hosts

=========================================================

In certain situations, URL reversing could generate scheme-relative URLs  (URLs

starting with two slashes), which could unexpectedly redirect a user  to a

different host. An attacker could exploit this, for example, by redirecting

users to a phishing site designed to ask for user's passwords.

To remedy this, URL reversing now ensures that no URL starts with two slashes

(//), replacing the second slash with its URL encoded counterpart (%2F). This

approach ensures that semantics stay the same, while making the URL relative to

the domain and not to the scheme.

File upload denial-of-service

=============================

Before this release, Django's file upload handing in its default configuration

may degrade to producing a huge number of ``os.stat()`` system calls when a

duplicate filename is uploaded. Since ``stat()`` may invoke IO, this may produce

a huge data-dependent slowdown that slowly worsens over time. The net result is

that given enough time, a user with the ability to upload files can cause poor

performance in the upload handler, eventually causing it to become very slow

simply by uploading 0-byte files. At this point, even a slow network connection

and few HTTP requests would be all that is necessary to make a site unavailable.

We've remedied the issue by changing the algorithm for generating file names

if a file with the uploaded name already exists.

:meth:`Storage.get_available_name()

<django.core.files.storage.Storage.get_available_name>` now appends an

underscore plus a random 7 character alphanumeric string (e.g. ``"_x3a1gho"``),

rather than iterating through an underscore followed by a number (e.g. ``"_1"``,

``"_2"``, etc.).

``RemoteUserMiddleware`` session hijacking

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When using the :class:`~django.contrib.auth.middleware.RemoteUserMiddleware`

and the ``RemoteUserBackend``, a change to the ``REMOTE_USER`` header between

requests without an intervening logout could result in the prior user's session

being co-opted by the subsequent user. The middleware now logs the user out on

a failed login attempt.

Data leakage via query string manipulation in ``contrib.admin``

===============================================================

In older versions of Django it was possible to reveal any field's data by

modifying the "popup" and "to_field" parameters of the query string on an admin

change form page. For example, requesting a URL like

``/admin/auth/user/?pop=1&t=password`` and viewing the page's HTML allowed

viewing the password hash of each user. While the admin requires users to have

permissions to view the change form pages in the first place, this could leak

data if you rely on users having access to view only certain fields on a model.

To address the issue, an exception will now be raised if a ``to_field`` value

that isn't a related field to a model that has been registered with the admin

is specified.