[1.10.x] Fixed CVE-2016-9014 -- Validated Host header when DEBUG=True.

This is a security fix.

docs/ref/settings.txt

@@ -90,14 +90,19 @@ If the ``Host`` header (or ``X-Forwarded-Host`` if
 list, the :meth:`django.http.HttpRequest.get_host()` method will raise
 :exc:`~django.core.exceptions.SuspiciousOperation`.
 
-When :setting:`DEBUG` is ``True`` or when running tests, host validation is
-disabled; any host will be accepted. Thus it's usually only necessary to set it
-in production.
+When :setting:`DEBUG` is ``True`` and ``ALLOWED_HOSTS`` is empty, the host
+is validated against ``['localhost', '127.0.0.1', '[::1]']``.
 
 This validation only applies via :meth:`~django.http.HttpRequest.get_host()`;
 if your code accesses the ``Host`` header directly from ``request.META`` you
 are bypassing this security protection.
 
+.. versionchanged:: 1.10.3
+
+    In older versions, ``ALLOWED_HOSTS`` wasn't checked if ``DEBUG=True``.
+    This was also changed in Django 1.9.11 and 1.8.16 to prevent a
+    DNS rebinding attack.
+
 .. setting:: APPEND_SLASH
 
 ``APPEND_SLASH``

docs/releases/1.10.3.txt

@@ -20,6 +20,28 @@ the ``manage.py test --keepdb`` option or if the user has an active session
 
 A randomly generated password is now used for each test run.
 
+DNS rebinding vulnerability when ``DEBUG=True``
+===============================================
+
+Older versions of Django don't validate the ``Host`` header against
+``settings.ALLOWED_HOSTS`` when ``settings.DEBUG=True``. This makes them
+vulnerable to a `DNS rebinding attack
+<http://benmmurphy.github.io/blog/2016/07/11/rails-webconsole-dns-rebinding/>`_.
+
+While Django doesn't ship a module that allows remote code execution, this is
+at least a cross-site scripting vector, which could be quite serious if
+developers load a copy of the production database in development or connect to
+some production services for which there's no development instance, for
+example. If a project uses a package like the ``django-debug-toolbar``, then
+the attacker could execute arbitrary SQL, which could be especially bad if the
+developers connect to the database with a superuser account.
+
+``settings.ALLOWED_HOSTS`` is now validated regardless of ``DEBUG``. For
+convenience, if ``ALLOWED_HOSTS`` is empty and ``DEBUG=True``, the following
+variations of localhost are allowed ``['localhost', '127.0.0.1', '::1']``. If
+your local settings file has your production ``ALLOWED_HOSTS`` value, you must
+now omit it to get those fallback values.
+
 Bugfixes
 ========
 

docs/releases/1.8.16.txt

@@ -19,3 +19,25 @@ the ``manage.py test --keepdb`` option or if the user has an active session
 (such as an attacker's connection).
 
 A randomly generated password is now used for each test run.
+
+DNS rebinding vulnerability when ``DEBUG=True``
+===============================================
+
+Older versions of Django don't validate the ``Host`` header against
+``settings.ALLOWED_HOSTS`` when ``settings.DEBUG=True``. This makes them
+vulnerable to a `DNS rebinding attack
+<http://benmmurphy.github.io/blog/2016/07/11/rails-webconsole-dns-rebinding/>`_.
+
+While Django doesn't ship a module that allows remote code execution, this is
+at least a cross-site scripting vector, which could be quite serious if
+developers load a copy of the production database in development or connect to
+some production services for which there's no development instance, for
+example. If a project uses a package like the ``django-debug-toolbar``, then
+the attacker could execute arbitrary SQL, which could be especially bad if the
+developers connect to the database with a superuser account.
+
+``settings.ALLOWED_HOSTS`` is now validated regardless of ``DEBUG``. For
+convenience, if ``ALLOWED_HOSTS`` is empty and ``DEBUG=True``, the following
+variations of localhost are allowed ``['localhost', '127.0.0.1', '::1']``. If
+your local settings file has your production ``ALLOWED_HOSTS`` value, you must
+now omit it to get those fallback values.

docs/releases/1.9.11.txt

@@ -19,3 +19,25 @@ the ``manage.py test --keepdb`` option or if the user has an active session
 (such as an attacker's connection).
 
 A randomly generated password is now used for each test run.
+
+DNS rebinding vulnerability when ``DEBUG=True``
+===============================================
+
+Older versions of Django don't validate the ``Host`` header against
+``settings.ALLOWED_HOSTS`` when ``settings.DEBUG=True``. This makes them
+vulnerable to a `DNS rebinding attack
+<http://benmmurphy.github.io/blog/2016/07/11/rails-webconsole-dns-rebinding/>`_.
+
+While Django doesn't ship a module that allows remote code execution, this is
+at least a cross-site scripting vector, which could be quite serious if
+developers load a copy of the production database in development or connect to
+some production services for which there's no development instance, for
+example. If a project uses a package like the ``django-debug-toolbar``, then
+the attacker could execute arbitrary SQL, which could be especially bad if the
+developers connect to the database with a superuser account.
+
+``settings.ALLOWED_HOSTS`` is now validated regardless of ``DEBUG``. For
+convenience, if ``ALLOWED_HOSTS`` is empty and ``DEBUG=True``, the following
+variations of localhost are allowed ``['localhost', '127.0.0.1', '::1']``. If
+your local settings file has your production ``ALLOWED_HOSTS`` value, you must
+now omit it to get those fallback values.