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

apollo13 · timgraham · commit da051da8df5e · 2014-08-20T11:43:43.000-04:00
This is a security fix. Disclosure following shortly.
diff --git a/django/core/urlresolvers.py b/django/core/urlresolvers.py
@@ -435,7 +435,11 @@ def _reverse_with_prefix(self, lookup_view, _prefix, *args, **kwargs):
                 candidate_pat = prefix_norm.replace('%', '%%') + result
                 if re.search('^%s%s' % (prefix_norm, pattern), candidate_pat % candidate_subs, re.UNICODE):
                     candidate_subs = dict((k, urlquote(v)) for (k, v) in candidate_subs.items())
-                    return candidate_pat % candidate_subs
+                    url = candidate_pat % candidate_subs
+                    # Don't allow construction of scheme relative urls.
+                    if url.startswith('//'):
+                        url = '/%%2F%s' % url[2:]
+                    return url
         # 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
         # error messages.
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/docs/releases/1.5.9.txt b/docs/releases/1.5.9.txt
@@ -5,3 +5,16 @@ Django 1.5.9 release notes
 *Under development*
 
 Django 1.5.9 fixes several security issues in 1.5.8.
+
+: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/docs/releases/1.6.6.txt b/docs/releases/1.6.6.txt
@@ -6,6 +6,19 @@ Django 1.6.6 release notes
 
 Django 1.6.6 fixes several security issues and bugs in 1.6.5.
 
+: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.
+
 Bugfixes
 ========
 
diff --git a/tests/urlpatterns_reverse/tests.py b/tests/urlpatterns_reverse/tests.py
@@ -147,6 +147,9 @@
     ('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/urlpatterns_reverse/urls.py b/tests/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
`@@ -147,6 +147,9 @@`
`147`	`147`	`('defaults', '/defaults_view2/3/', [], {'arg1': 3, 'arg2': 2}),`
`148`	`148`	`('defaults', NoReverseMatch, [], {'arg1': 3, 'arg2': 3}),`
`149`	`149`	`('defaults', NoReverseMatch, [], {'arg2': 1}),`
	`150`	`+`
	`151`	`+ # Security tests`
	`152`	`+ ('security', '/%2Fexample.com/security/', ['/example.com'], {}),`
`150`	`153`	`)`
`151`	`154`
`152`	`155`	`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`	`)`