# HG changeset patch
# User Senthil Kumaran <senthil@uthcode.com>
# Date 1469882993 25200
# Node ID ba915d561667fa0584ad89f8d5a844fd43803c0d
# Parent c8c1ea94379a7706638f1571988576d504d7fc98
Prevent HTTPoxy attack (CVE-2016-1000110)
Ignore the HTTP_PROXY variable when REQUEST_METHOD environment is set, which
indicates that the script is in CGI mode.
Issue reported and patch contributed by RĂ©mi Rampin.
diff --git a/Doc/howto/urllib2.rst b/Doc/howto/urllib2.rst
--- a/Doc/howto/urllib2.rst
+++ b/Doc/howto/urllib2.rst
@@ -523,6 +523,11 @@ setting up a `Basic Authentication`_ handler: ::
through a proxy. However, this can be enabled by extending urllib2 as
shown in the recipe [#]_.
+.. note::
+
+ ``HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set; see
+ the documentation on :func:`~urllib.getproxies`.
+
Sockets and Layers
==================
diff --git a/Doc/library/urllib.rst b/Doc/library/urllib.rst
--- a/Doc/library/urllib.rst
+++ b/Doc/library/urllib.rst
@@ -293,6 +293,17 @@ Utility functions
find it, looks for proxy information from Mac OSX System Configuration for
Mac OS X and Windows Systems Registry for Windows.
+ .. note::
+
+ If the environment variable ``REQUEST_METHOD`` is set, which usually
+ indicates your script is running in a CGI environment, the environment
+ variable ``HTTP_PROXY`` (uppercase ``_PROXY``) will be ignored. This is
+ because that variable can be injected by a client using the "Proxy:"
+ HTTP header. If you need to use an HTTP proxy in a CGI environment,
+ either use ``ProxyHandler`` explicitly, or make sure the variable name
+ is in lowercase (or at least the ``_proxy`` suffix).
+
+
.. note::
urllib also exposes certain utility functions like splittype, splithost and
others parsing url into various components. But it is recommended to use
diff --git a/Doc/library/urllib2.rst b/Doc/library/urllib2.rst
--- a/Doc/library/urllib2.rst
+++ b/Doc/library/urllib2.rst
@@ -229,6 +229,11 @@ The following classes are provided:
To disable autodetected proxy pass an empty dictionary.
+ .. note::
+
+ ``HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set;
+ see the documentation on :func:`~urllib.getproxies`.
+
.. class:: HTTPPasswordMgr()
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -161,6 +161,18 @@ class ProxyTests(unittest.TestCase):
self.env.set('NO_PROXY', 'localhost, anotherdomain.com, newdomain.com')
self.assertTrue(urllib.proxy_bypass_environment('anotherdomain.com'))
+ def test_proxy_cgi_ignore(self):
+ try:
+ self.env.set('HTTP_PROXY', 'http://somewhere:3128')
+ proxies = urllib.getproxies_environment()
+ self.assertEqual('http://somewhere:3128', proxies['http'])
+ self.env.set('REQUEST_METHOD', 'GET')
+ proxies = urllib.getproxies_environment()
+ self.assertNotIn('http', proxies)
+ finally:
+ self.env.unset('REQUEST_METHOD')
+ self.env.unset('HTTP_PROXY')
+
class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin):
"""Test urlopen() opening a fake http connection."""
diff --git a/Lib/urllib.py b/Lib/urllib.py
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1387,6 +1387,12 @@ def getproxies_environment():
name = name.lower()
if value and name[-6:] == '_proxy':
proxies[name[:-6]] = value
+ # CVE-2016-1000110 - If we are running as CGI script, forget HTTP_PROXY
+ # (non-all-lowercase) as it may be set from the web server by a "Proxy:"
+ # header from the client
+ # If "proxy" is lowercase, it will still be used thanks to the next block
+ if 'REQUEST_METHOD' in os.environ:
+ proxies.pop('http', None)
return proxies
def proxy_bypass_environment(host):