diff --git a/Lib/http/server.py b/Lib/http/server.py
index 2d2300c2aeab3c..6bf9084341a659 100644
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -330,6 +330,13 @@ def parse_request(self):
return False
self.command, self.path = command, path
+ # gh-87389: The purpose of replacing '//' with '/' is to protect
+ # against open redirect attacks possibly triggered if the path starts
+ # with '//' because http clients treat //path as an absolute URI
+ # without scheme (similar to http://path) rather than a path.
+ if self.path.startswith('//'):
+ self.path = '/' + self.path.lstrip('/') # Reduce to a single /
+
# Examine the headers and look for a Connection directive.
try:
self.headers = http.client.parse_headers(self.rfile,
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
index c1494d29ca8707..4acf7a6fea4485 100644
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -331,7 +331,7 @@ class request_handler(NoLogRequestHandler, SimpleHTTPRequestHandler):
pass
def setUp(self):
- BaseTestCase.setUp(self)
+ super().setUp()
self.cwd = os.getcwd()
basetempdir = tempfile.gettempdir()
os.chdir(basetempdir)
@@ -359,7 +359,7 @@ def tearDown(self):
except:
pass
finally:
- BaseTestCase.tearDown(self)
+ super().tearDown()
def check_status_and_reason(self, response, status, data=None):
def close_conn():
@@ -415,6 +415,55 @@ def test_undecodable_filename(self):
self.check_status_and_reason(response, HTTPStatus.OK,
data=support.TESTFN_UNDECODABLE)
+ def test_get_dir_redirect_location_domain_injection_bug(self):
+ """Ensure //evil.co/..%2f../../X does not put //evil.co/ in Location.
+
+ //netloc/ in a Location header is a redirect to a new host.
+ https://github.com/python/cpython/issues/87389
+
+ This checks that a path resolving to a directory on our server cannot
+ resolve into a redirect to another server.
+ """
+ os.mkdir(os.path.join(self.tempdir, 'existing_directory'))
+ url = f'/python.org/..%2f..%2f..%2f..%2f..%2f../%0a%0d/../{self.tempdir_name}/existing_directory'
+ expected_location = f'{url}/' # /python.org.../ single slash single prefix, trailing slash
+ # Canonicalizes to /tmp/tempdir_name/existing_directory which does
+ # exist and is a dir, triggering the 301 redirect logic.
+ response = self.request(url)
+ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY)
+ location = response.getheader('Location')
+ self.assertEqual(location, expected_location, msg='non-attack failed!')
+
+ # //python.org... multi-slash prefix, no trailing slash
+ attack_url = f'/{url}'
+ response = self.request(attack_url)
+ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY)
+ location = response.getheader('Location')
+ self.assertFalse(location.startswith('//'), msg=location)
+ self.assertEqual(location, expected_location,
+ msg='Expected Location header to start with a single / and '
+ 'end with a / as this is a directory redirect.')
+
+ # ///python.org... triple-slash prefix, no trailing slash
+ attack3_url = f'//{url}'
+ response = self.request(attack3_url)
+ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY)
+ self.assertEqual(response.getheader('Location'), expected_location)
+
+ # If the second word in the http request (Request-URI for the http
+ # method) is a full URI, we don't worry about it, as that'll be parsed
+ # and reassembled as a full URI within BaseHTTPRequestHandler.send_head
+ # so no errant scheme-less //netloc//evil.co/ domain mixup can happen.
+ attack_scheme_netloc_2slash_url = f'https://pypi.org/{url}'
+ expected_scheme_netloc_location = f'{attack_scheme_netloc_2slash_url}/'
+ response = self.request(attack_scheme_netloc_2slash_url)
+ self.check_status_and_reason(response, HTTPStatus.MOVED_PERMANENTLY)
+ location = response.getheader('Location')
+ # We're just ensuring that the scheme and domain make it through, if
+ # there are or aren't multiple slashes at the start of the path that
+ # follows that isn't important in this Location: header.
+ self.assertTrue(location.startswith('https://pypi.org/'), msg=location)
+
def test_get(self):
#constructs the path relative to the root directory of the HTTPServer
response = self.request(self.base_url + '/test')
diff --git a/Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst b/Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst
new file mode 100644
index 00000000000000..029d437190deb5
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2022-06-15-20-09-23.gh-issue-87389.QVaC3f.rst
@@ -0,0 +1,3 @@
+:mod:`http.server`: Fix an open redirection vulnerability in the HTTP server
+when an URI path starts with ``//``. Vulnerability discovered, and initial
+fix proposed, by Hamza Avvan.
pFad - Phonifier reborn
Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.
Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
Alternative Proxies:
Alternative Proxy
pFad Proxy
pFad v3 Proxy
pFad v4 Proxy