https://hg.python.org/cpython/rev/3c19023c9fec changeset: 102502:3c19023c9fec branch: 3.4 parent: 102341:17ec4d58c046 parent: 102501:95b09ccc8a3e user: Senthil Kumaran <senthil@uthcode.com> date: Sat Jul 30 23:34:34 2016 -0700 summary: [merge from 3.3] 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 #27568 Reported and patch contributed by Rémi Rampin. files: Doc/howto/urllib2.rst | 5 +++++ Doc/library/urllib.request.rst | 13 +++++++++++++ Lib/test/test_urllib.py | 13 +++++++++++++ Lib/urllib/request.py | 7 +++++++ Misc/NEWS | 4 ++++ 5 files changed, 42 insertions(+), 0 deletions(-) diff --git a/Doc/howto/urllib2.rst b/Doc/howto/urllib2.rst --- a/Doc/howto/urllib2.rst +++ b/Doc/howto/urllib2.rst @@ -538,6 +538,11 @@ through a proxy. However, this can be enabled by extending urllib.request as shown in the recipe [#]_. +.. note:: + + `HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set; see + the documentation on :func:`~urllib.request.getproxies`. + Sockets and Layers ================== diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst --- a/Doc/library/urllib.request.rst +++ b/Doc/library/urllib.request.rst @@ -166,6 +166,14 @@ cannot 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 use + ``ProxyHandler`` explicitly. The following classes are provided: @@ -268,6 +276,11 @@ 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.request.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 @@ -222,6 +222,19 @@ self.env.set('NO_PROXY', 'localhost, anotherdomain.com, newdomain.com') self.assertTrue(urllib.request.proxy_bypass_environment('anotherdomain.com')) + def test_proxy_cgi_ignore(self): + try: + self.env.set('HTTP_PROXY', 'http://somewhere:3128') + proxies = urllib.request.getproxies_environment() + self.assertEqual('http://somewhere:3128', proxies['http']) + self.env.set('REQUEST_METHOD', 'GET') + proxies = urllib.request.getproxies_environment() + self.assertNotIn('http', proxies) + finally: + self.env.unset('REQUEST_METHOD') + self.env.unset('HTTP_PROXY') + + class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin, FakeFTPMixin): """Test urlopen() opening a fake http connection.""" diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py --- a/Lib/urllib/request.py +++ b/Lib/urllib/request.py @@ -2337,6 +2337,13 @@ 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 'REQUEST_METHOD' in os.environ: + proxies.pop('http', None) + return proxies def proxy_bypass_environment(host): diff --git a/Misc/NEWS b/Misc/NEWS --- a/Misc/NEWS +++ b/Misc/NEWS @@ -13,6 +13,10 @@ Library ------- +- Issue #27568: 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. + Tests ----- -- Repository URL: https://hg.python.org/cpython