Fixed #27912, CVE-2017-7233 -- Fixed is_safe_url() with numeric URLs.

This is a security fix.

5 files changed, 93 insertions, 3 deletions

diff --git a/django/utils/http.py b/django/utils/http.py
index bd2daad4b2..1433df4ff0 100644
--- a/django/utils/http.py
+++ b/django/utils/http.py
@@ -7,8 +7,9 @@ import warnings
 from binascii import Error as BinasciiError
 from email.utils import formatdate
 from urllib.parse import (
-    quote, quote_plus, unquote, unquote_plus, urlencode as original_urlencode,
-    urlparse,
+    ParseResult, SplitResult, _coerce_args, _splitnetloc, _splitparams, quote,
+    quote_plus, scheme_chars, unquote, unquote_plus,
+    urlencode as original_urlencode, uses_params,
 )
 
 from django.core.exceptions import TooManyFieldsSent
@@ -293,12 +294,62 @@ def is_safe_url(url, host=None, allowed_hosts=None, require_https=False):
             _is_safe_url(url.replace('\\', '/'), allowed_hosts, require_https=require_https))
 
 
+# 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."""
+    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)
+
+
+# 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."""
+    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)
+
+
 def _is_safe_url(url, allowed_hosts, require_https=False):
     # 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
diff --git a/docs/releases/1.10.7.txt b/docs/releases/1.10.7.txt
index 0c79347cc3..c5caa65143 100644
--- a/docs/releases/1.10.7.txt
+++ b/docs/releases/1.10.7.txt
@@ -6,6 +6,18 @@ Django 1.10.7 release notes
 
 Django 1.10.7 fixes two security issues and a bug in 1.10.6.
 
+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()``
 =============================================================================
 
diff --git a/docs/releases/1.8.18.txt b/docs/releases/1.8.18.txt
index 7b1e08046c..f41c7d080f 100644
--- a/docs/releases/1.8.18.txt
+++ b/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()``
 =============================================================================
 
diff --git a/docs/releases/1.9.13.txt b/docs/releases/1.9.13.txt
index f9d203eafe..4828096da9 100644
--- a/docs/releases/1.9.13.txt
+++ b/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()``
 =============================================================================
 
diff --git a/tests/utils_tests/test_http.py b/tests/utils_tests/test_http.py
index 281fb77fbb..80e795d3af 100644
--- a/tests/utils_tests/test_http.py
+++ b/tests/utils_tests/test_http.py
@@ -97,6 +97,8 @@ 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',
         )
         for bad_url in bad_urls:
@@ -117,6 +119,7 @@ class TestUtilsHttp(unittest.TestCase):
             '//testserver/',
             'http://testserver/confirm?email=me@example.com',
             '/url%20with%20spaces/',
+            'path/http:2222222222',
         )
         for good_url in good_urls:
             with ignore_warnings(category=RemovedInDjango21Warning):