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

This is a security fix. Disclosure following shortly.

django/core/urlresolvers.py

@@ -426,6 +426,8 @@ class RegexURLResolver(LocaleRegexProvider):
                     unicode_kwargs = dict([(k, force_text(v)) for (k, v) in kwargs.items()])
                     candidate = (prefix_norm.replace('%', '%%') + result) % unicode_kwargs
                 if re.search('^%s%s' % (prefix_norm, 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

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.

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.

tests/regressiontests/urlpatterns_reverse/tests.py

@@ -143,6 +143,9 @@ test_data = (
     ('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):

tests/regressiontests/urlpatterns_reverse/urls.py

@@ -71,4 +71,7 @@ urlpatterns = patterns('',
     (r'defaults_view2/(?P<arg1>\d+)/', 'defaults_view', {'arg2': 2}, 'defaults'),
 
     url('^includes/', include(other_patterns)),
+
+    # Security tests
+    url('(.+)/security/$', empty_view, name='security'),
 )