Fixed is_safe_url() to reject URLs that use a scheme other than HTTP/S.

jacobian · jacobian · commit ec67af0bd609 · 2013-08-13T11:00:13.000-05:00
This is a security fix; disclosure to follow shortly.
diff --git a/django/contrib/auth/tests/views.py b/django/contrib/auth/tests/views.py
@@ -309,7 +309,8 @@ def test_security_check(self, password='password'):
         for bad_url in ('http://example.com',
                         'https://example.com',
                         'ftp://exampel.com',
-                        '//example.com'):
+                        '//example.com',
+                        'javascript:alert("XSS")'):
 
             nasty_url = '%(url)s?%(next)s=%(bad_url)s' % {
                 'url': login_url,
@@ -330,6 +331,7 @@ def test_security_check(self, password='password'):
                          '/view?param=ftp://exampel.com',
                          'view/?param=//example.com',
                          'https:///',
+                         'HTTPS:///',
                          '//testserver/',
                          '/url%20with%20spaces/'):  # see ticket #12534
             safe_url = '%(url)s?%(next)s=%(good_url)s' % {
@@ -467,7 +469,8 @@ def test_security_check(self, password='password'):
         for bad_url in ('http://example.com',
                         'https://example.com',
                         'ftp://exampel.com',
-                        '//example.com'):
+                        '//example.com',
+                        'javascript:alert("XSS")'):
             nasty_url = '%(url)s?%(next)s=%(bad_url)s' % {
                 'url': logout_url,
                 'next': REDIRECT_FIELD_NAME,
@@ -486,6 +489,7 @@ def test_security_check(self, password='password'):
                          '/view?param=ftp://exampel.com',
                          'view/?param=//example.com',
                          'https:///',
+                         'HTTPS:///',
                          '//testserver/',
                          '/url%20with%20spaces/'):  # see ticket #12534
             safe_url = '%(url)s?%(next)s=%(good_url)s' % {
diff --git a/django/utils/http.py b/django/utils/http.py
@@ -228,11 +228,12 @@ def same_origin(url1, url2):
 def is_safe_url(url, host=None):
     """
     Return ``True`` if the url is a safe redirection (i.e. it doesn't point to
-    a different host).
+    a different host and uses a safe scheme).
 
     Always returns ``False`` on an empty url.
     """
     if not url:
         return False
-    netloc = urlparse.urlparse(url)[1]
-    return not netloc or netloc == host
+    url_info = urlparse.urlparse(url)
+    return (not url_info[1] or url_info[1] == host) and \
+        (not url_info[0] or url_info[0] in ['http', 'https'])
