commit 520321417d87c6bea9ac55354b9f29eba0a0a851
Author: Philippe Makowski <pmakowski@espelida.com>
Date:   Sat Aug 13 18:21:22 2016 +0200

    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 Rémi Rampin.

diff --git a/Doc/howto/urllib2.rst b/Doc/howto/urllib2.rst
index 0be740e..7b05eea 100644
--- 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
index b2a817d..da8d573 100644
--- a/Doc/library/urllib.rst
+++ b/Doc/library/urllib.rst
@@ -288,6 +288,16 @@ 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
index f599894..34f6e13 100644
--- a/Doc/library/urllib2.rst
+++ b/Doc/library/urllib2.rst
@@ -224,6 +224,11 @@ 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/urllib.py b/Lib/urllib.py
index 2408cb8..fca4494 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1373,11 +1373,30 @@ def getproxies_environment():
     [Fancy]URLopener constructor.
 
     """
+    # Get all variables
     proxies = {}
     for name, value in os.environ.items():
         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)
+
+    # Get lowercase variables
+
+    for name, value in os.environ.items():
+        if name[-6:] == '_proxy':
+            name = name.lower()
+            if value:
+                proxies[name[:-6]] = value
+            else:
+                proxies.pop(name[:-6], None)
+
     return proxies
 
 def proxy_bypass_environment(host):