From 316bc3fc9437c5960c24baceb93c73f1939711e4 Mon Sep 17 00:00:00 2001
From: Florian Apolloner <florian@apolloner.eu>
Date: Wed, 11 Nov 2015 20:10:55 +0100
Subject: [PATCH] Fixed a settings leak possibility in the date template
 filter.

This is a security fix.
---
 django/utils/formats.py  | 20 ++++++++++++++++++++
 docs/releases/1.7.11.txt | 15 ++++++++++++++-
 docs/releases/1.8.7.txt  | 15 ++++++++++++++-
 tests/i18n/tests.py      |  3 +++
 4 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/django/utils/formats.py b/django/utils/formats.py
index d2bdda458e0..8334682e684 100644
--- a/django/utils/formats.py
+++ b/django/utils/formats.py
@@ -30,6 +30,24 @@ ISO_INPUT_FORMATS = {
 }
 
 
+FORMAT_SETTINGS = frozenset([
+    'DECIMAL_SEPARATOR',
+    'THOUSAND_SEPARATOR',
+    'NUMBER_GROUPING',
+    'FIRST_DAY_OF_WEEK',
+    'MONTH_DAY_FORMAT',
+    'TIME_FORMAT',
+    'DATE_FORMAT',
+    'DATETIME_FORMAT',
+    'SHORT_DATE_FORMAT',
+    'SHORT_DATETIME_FORMAT',
+    'YEAR_MONTH_FORMAT',
+    'DATE_INPUT_FORMATS',
+    'TIME_INPUT_FORMATS',
+    'DATETIME_INPUT_FORMATS',
+])
+
+
 def reset_format_cache():
     """Clear any cached formats.
 
@@ -92,6 +110,8 @@ def get_format(format_type, lang=None, use_l10n=None):
     be localized (or not), overriding the value of settings.USE_L10N.
     """
     format_type = force_str(format_type)
+    if format_type not in FORMAT_SETTINGS:
+        return format_type
     if use_l10n or (use_l10n is None and settings.USE_L10N):
         if lang is None:
             lang = get_language()
diff --git a/docs/releases/1.7.11.txt b/docs/releases/1.7.11.txt
index 7c6153eab1d..8f2f5e7541e 100644
--- a/docs/releases/1.7.11.txt
+++ b/docs/releases/1.7.11.txt
@@ -4,7 +4,20 @@ Django 1.7.11 release notes
 
 *Under development*
 
-Django 1.7.11 fixes a data loss bug in 1.7.10.
+Django 1.7.11 fixes a security issue and a data loss bug in 1.7.10.
+
+Fixed settings leak possibility in ``date`` template filter
+===========================================================
+
+If an application allows users to specify an unvalidated format for dates and
+passes this format to the :tfilter:`date` filter, e.g.
+``{{ last_updated|date:user_date_format }}``, then a malicious user could
+obtain any secret in the application's settings by specifying a settings key
+instead of a date format. e.g. ``"SECRET_KEY"`` instead of ``"j/m/Y"``.
+
+To remedy this, the underlying function used by the ``date`` template filter,
+``django.utils.formats.get_format()``, now only allows accessing the date/time
+formatting settings.
 
 Bugfixes
 ========
diff --git a/docs/releases/1.8.7.txt b/docs/releases/1.8.7.txt
index 25f7712f106..77d5e9f901e 100644
--- a/docs/releases/1.8.7.txt
+++ b/docs/releases/1.8.7.txt
@@ -4,11 +4,24 @@ Django 1.8.7 release notes
 
 *Under development*
 
-Django 1.8.7 fixes several bugs in 1.8.6.
+Django 1.8.7 fixes a security issue and several bugs in 1.8.6.
 
 Additionally, Django's vendored version of six, :mod:`django.utils.six`, has
 been upgraded to the latest release (1.10.0).
 
+Fixed settings leak possibility in ``date`` template filter
+===========================================================
+
+If an application allows users to specify an unvalidated format for dates and
+passes this format to the :tfilter:`date` filter, e.g.
+``{{ last_updated|date:user_date_format }}``, then a malicious user could
+obtain any secret in the application's settings by specifying a settings key
+instead of a date format. e.g. ``"SECRET_KEY"`` instead of ``"j/m/Y"``.
+
+To remedy this, the underlying function used by the ``date`` template filter,
+``django.utils.formats.get_format()``, now only allows accessing the date/time
+formatting settings.
+
 Bugfixes
 ========
 
diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
index 1de7b11b811..fd332c596e7 100644
--- a/tests/i18n/tests.py
+++ b/tests/i18n/tests.py
@@ -1249,6 +1249,9 @@ class FormattingTests(SimpleTestCase):
                 '<input id="id_cents_paid" name="cents_paid" type="hidden" value="59,47" />'
             )
 
+    def test_format_arbitrary_settings(self):
+        self.assertEqual(get_format('DEBUG'), 'DEBUG')
+
 
 class MiscTests(SimpleTestCase):