[1.4.x] Prevented reverse() from generating URLs pointing to other hosts.

apollo13 · timgraham · commit c2fe73133b62 · 2014-08-11T09:04:23.000-04:00
This is a security fix. Disclosure following shortly.
diff --git a/django/core/urlresolvers.py b/django/core/urlresolvers.py
@@ -406,6 +406,8 @@ def _reverse_with_prefix(self, lookup_view, _prefix, *args, **kwargs):
                     unicode_kwargs = dict([(k, force_unicode(v)) for (k, v) in kwargs.items()])
                     candidate = (prefix_norm + result) % unicode_kwargs
                 if re.search(u'^%s%s' % (_prefix, pattern), candidate, re.UNICODE):
+                    if candidate.startswith('//'):
+                        candidate = '/%%2F%s' % candidate[2:]
                     return candidate
         # lookup_view can be URL label, or dotted path, or callable, Any of
         # these can be passed in at the top, but callables are not friendly in
diff --git a/docs/releases/1.4.14.txt b/docs/releases/1.4.14.txt
@@ -5,3 +5,16 @@ Django 1.4.14 release notes
 *Under development*
 
 Django 1.4.14 fixes several security issues in 1.4.13.
+
+:func:`~django.core.urlresolvers.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.
diff --git a/tests/regressiontests/urlpatterns_reverse/tests.py b/tests/regressiontests/urlpatterns_reverse/tests.py
@@ -142,6 +142,9 @@
     ('defaults', '/defaults_view2/3/', [], {'arg1': 3, 'arg2': 2}),
     ('defaults', NoReverseMatch, [], {'arg1': 3, 'arg2': 3}),
     ('defaults', NoReverseMatch, [], {'arg2': 1}),
+
+    # Security tests
+    ('security', '/%2Fexample.com/security/', ['/example.com'], {}),
 )
 
 class NoURLPatternsTests(TestCase):
diff --git a/tests/regressiontests/urlpatterns_reverse/urls.py b/tests/regressiontests/urlpatterns_reverse/urls.py
@@ -71,4 +71,7 @@
     (r'defaults_view2/(?P<arg1>\d+)/', 'defaults_view', {'arg2': 2}, 'defaults'),
 
     url('^includes/', include(other_patterns)),
+
+    # Security tests
+    url('(.+)/security/$', empty_view, name='security'),
 )

Original file line number	Diff line number	Diff line change
`@@ -142,6 +142,9 @@`
`142`	`142`	`('defaults', '/defaults_view2/3/', [], {'arg1': 3, 'arg2': 2}),`
`143`	`143`	`('defaults', NoReverseMatch, [], {'arg1': 3, 'arg2': 3}),`
`144`	`144`	`('defaults', NoReverseMatch, [], {'arg2': 1}),`
	`145`	`+`
	`146`	`+ # Security tests`
	`147`	`+ ('security', '/%2Fexample.com/security/', ['/example.com'], {}),`
`145`	`148`	`)`
`146`	`149`
`147`	`150`	`class NoURLPatternsTests(TestCase):`
Original file line number	Diff line number	Diff line change
`@@ -71,4 +71,7 @@`
`71`	`71`	`(r'defaults_view2/(?P<arg1>\d+)/', 'defaults_view', {'arg2': 2}, 'defaults'),`
`72`	`72`
`73`	`73`	`url('^includes/', include(other_patterns)),`
	`74`	`+`
	`75`	`+ # Security tests`
	`76`	`+ url('(.+)/security/$', empty_view, name='security'),`
`74`	`77`	`)`