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[SECURITY] [DLA 143-1] python-django security update

Package        : python-django
Version        : 1.2.3-3+squeeze12
CVE ID         : CVE-2015-0219 CVE-2015-0220 CVE-2015-0221

Multiple security issues have been found in Django:

For Debian 6 Squeeeze, they have been fixed in version 1.2.3-3+squeeze12
of python-django. Here is what the upstream developers have to say about
those issues:

CVE-2015-0219 - WSGI header spoofing via underscore/dash conflation

    When HTTP headers are placed into the WSGI environ, they are
    normalized by converting to uppercase, converting all dashes to
    underscores, and prepending HTTP_. For instance, a header X-Auth-User
    would become HTTP_X_AUTH_USER in the WSGI environ (and thus also in
    Django's request.META dictionary).

    Unfortunately, this means that the WSGI environ cannot distinguish
    between headers containing dashes and headers containing underscores:
    X-Auth-User and X-Auth_User both become HTTP_X_AUTH_USER. This means
    that if a header is used in a security-sensitive way (for instance,
    passing authentication information along from a front-end proxy), even
    if the proxy carefully strips any incoming value for X-Auth-User, an
    attacker may be able to provide an X-Auth_User header (with
    underscore) and bypass this protection.

    In order to prevent such attacks, both Nginx and Apache 2.4+ strip
    all headers containing underscores from incoming requests by
    default. Django's built-in development server now does the same.
    Django's development server is not recommended for production use,
    but matching the behavior of common production servers reduces the
    surface area for behavior changes during deployment.

CVE-2015-0220 - Possible XSS attack via user-supplied redirect URLs

    Django relies on user input in some cases (e.g.
    django.contrib.auth.views.login() and i18n) to redirect the user to an
    "on success" URL. The security checks for these redirects (namely
    django.util.http.is_safe_url()) didn't strip leading whitespace on the
    tested URL and as such considered URLs like "\njavascript:..." safe. If
    a developer relied on is_safe_url() to provide safe redirect targets
    and put such a URL into a link, they could suffer from a XSS attack.
    This bug doesn't affect Django currently, since we only put this URL
    into the Location response header and browsers seem to ignore
    JavaScript there.

CVE-2015-0221 - Denial-of-service attack against django.views.static.serve

    In older versions of Django, the django.views.static.serve() view read
    the files it served one line at a time. Therefore, a big file with no
    newlines would result in memory usage equal to the size of that file.
    An attacker could exploit this and launch a denial-of-service attack
    by simultaneously requesting many large files. This view now reads the
    file in chunks to prevent large memory usage.

    Note, however, that this view has always carried a warning that it is
    not hardened for production use and should be used only as a
    development aid. Now may be a good time to audit your project and
    serve your files in production using a real front-end web server if
    you are not doing so.

Note that the version of Django in use in Debian 6 Squeeze was not
affected by CVE-2015-0222 (Database denial-of-service with
ModelMultipleChoiceField) since that feature does not exist
in this version.

Raphaël Hertzog ◈ Debian Developer

Support Debian LTS: http://www.freexian.com/services/debian-lts.html
Learn to master Debian: http://debian-handbook.info/get/

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