[1.9.x] Fixed #27912, CVE-2017-7233 -- Fixed is_safe_url() with numeric URLs.

This is a security fix.

django/utils/http.py

@@ -15,7 +15,18 @@ from django.utils.encoding import force_bytes, force_str, force_text
 from django.utils.functional import allow_lazy
 from django.utils.six.moves.urllib.parse import (
     quote, quote_plus, unquote, unquote_plus, urlencode as original_urlencode,
-    urlparse,
+)
+
+if six.PY2:
+    from urlparse import (
+        ParseResult, SplitResult, _splitnetloc, _splitparams, scheme_chars,
+        uses_params,
+    )
+    _coerce_args = None
+else:
+    from urllib.parse import (
+        ParseResult, SplitResult, _coerce_args, _splitnetloc, _splitparams,
+        scheme_chars, uses_params,
     )
 
 ETAG_MATCH = re.compile(r'(?:W/)?"((?:\\.|[^"])*)"')
@@ -300,12 +311,64 @@ def is_safe_url(url, host=None):
     return _is_safe_url(url, host) and _is_safe_url(url.replace('\\', '/'), host)
 
 
+# Copied from urllib.parse.urlparse() but uses fixed urlsplit() function.
+def _urlparse(url, scheme='', allow_fragments=True):
+    """Parse a URL into 6 components:
+    <scheme>://<netloc>/<path>;<params>?<query>#<fragment>
+    Return a 6-tuple: (scheme, netloc, path, params, query, fragment).
+    Note that we don't break the components up in smaller bits
+    (e.g. netloc is a single string) and we don't expand % escapes."""
+    if _coerce_args:
+        url, scheme, _coerce_result = _coerce_args(url, scheme)
+    splitresult = _urlsplit(url, scheme, allow_fragments)
+    scheme, netloc, url, query, fragment = splitresult
+    if scheme in uses_params and ';' in url:
+        url, params = _splitparams(url)
+    else:
+        params = ''
+    result = ParseResult(scheme, netloc, url, params, query, fragment)
+    return _coerce_result(result) if _coerce_args else result
+
+
+# Copied from urllib.parse.urlsplit() with
+# https://github.com/python/cpython/pull/661 applied.
+def _urlsplit(url, scheme='', allow_fragments=True):
+    """Parse a URL into 5 components:
+    <scheme>://<netloc>/<path>?<query>#<fragment>
+    Return a 5-tuple: (scheme, netloc, path, query, fragment).
+    Note that we don't break the components up in smaller bits
+    (e.g. netloc is a single string) and we don't expand % escapes."""
+    if _coerce_args:
+        url, scheme, _coerce_result = _coerce_args(url, scheme)
+    allow_fragments = bool(allow_fragments)
+    netloc = query = fragment = ''
+    i = url.find(':')
+    if i > 0:
+        for c in url[:i]:
+            if c not in scheme_chars:
+                break
+        else:
+            scheme, url = url[:i].lower(), url[i + 1:]
+
+    if url[:2] == '//':
+        netloc, url = _splitnetloc(url, 2)
+        if (('[' in netloc and ']' not in netloc) or
+                (']' in netloc and '[' not in netloc)):
+            raise ValueError("Invalid IPv6 URL")
+    if allow_fragments and '#' in url:
+        url, fragment = url.split('#', 1)
+    if '?' in url:
+        url, query = url.split('?', 1)
+    v = SplitResult(scheme, netloc, url, query, fragment)
+    return _coerce_result(v) if _coerce_args else v
+
+
 def _is_safe_url(url, host):
     # Chrome considers any URL with more than two slashes to be absolute, but
     # urlparse is not so flexible. Treat any url with three slashes as unsafe.
     if url.startswith('///'):
         return False
-    url_info = urlparse(url)
+    url_info = _urlparse(url)
     # Forbid URLs like http:///example.com - with a scheme, but without a hostname.
     # In that URL, example.com is not the hostname but, a path component. However,
     # Chrome will still consider example.com to be the hostname, so we must not

docs/releases/1.8.18.txt

@@ -6,6 +6,18 @@ Django 1.8.18 release notes
 
 Django 1.8.18 fixes two security issues in 1.8.17.
 
+CVE-2017-7233: Open redirect and possible XSS attack via user-supplied numeric redirect URLs
+============================================================================================
+
+Django relies on user input in some cases  (e.g.
+:func:`django.contrib.auth.views.login` and :doc:`i18n </topics/i18n/index>`)
+to redirect the user to an "on success" URL. The security check for these
+redirects (namely ``django.utils.http.is_safe_url()``) considered some numeric
+URLs (e.g. ``http:999999999``) "safe" when they shouldn't be.
+
+Also, if a developer relies on ``is_safe_url()`` to provide safe redirect
+targets and puts such a URL into a link, they could suffer from an XSS attack.
+
 CVE-2017-7234: Open redirect vulnerability in ``django.views.static.serve()``
 =============================================================================
 

docs/releases/1.9.13.txt

@@ -7,6 +7,18 @@ Django 1.9.13 release notes
 Django 1.9.13 fixes two security issues and a bug in 1.9.12. This is the final
 release of the 1.9.x series.
 
+CVE-2017-7233: Open redirect and possible XSS attack via user-supplied numeric redirect URLs
+============================================================================================
+
+Django relies on user input in some cases  (e.g.
+:func:`django.contrib.auth.views.login` and :doc:`i18n </topics/i18n/index>`)
+to redirect the user to an "on success" URL. The security check for these
+redirects (namely ``django.utils.http.is_safe_url()``) considered some numeric
+URLs (e.g. ``http:999999999``) "safe" when they shouldn't be.
+
+Also, if a developer relies on ``is_safe_url()`` to provide safe redirect
+targets and puts such a URL into a link, they could suffer from an XSS attack.
+
 CVE-2017-7234: Open redirect vulnerability in ``django.views.static.serve()``
 =============================================================================
 

tests/utils_tests/test_http.py

@@ -98,6 +98,8 @@ class TestUtilsHttp(unittest.TestCase):
                         r'http://testserver\me:pass@example.com',
                         r'http://testserver\@example.com',
                         r'http:\\testserver\confirm\me@example.com',
+                        'http:999999999',
+                        'ftp:9999999999',
                         '\n'):
             self.assertFalse(http.is_safe_url(bad_url, host='testserver'), "%s should be blocked" % bad_url)
         for good_url in ('/view/?param=http://example.com',
@@ -108,7 +110,8 @@ class TestUtilsHttp(unittest.TestCase):
                      'HTTPS://testserver/',
                      '//testserver/',
                      'http://testserver/confirm?email=me@example.com',
-                     '/url%20with%20spaces/'):
+                     '/url%20with%20spaces/',
+                     'path/http:2222222222'):
             self.assertTrue(http.is_safe_url(good_url, host='testserver'), "%s should be allowed" % good_url)
 
         if six.PY2: