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bpo-36338: Reject hostname with [ at position > 0 #14896

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bpo-36338: Reject hostname with [ at position > 0 #14896

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13 changes: 13 additions & 0 deletions Lib/test/test_urlparse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -531,6 +531,19 @@ def test_urlsplit_scoped_IPv6(self):
self.assertEqual(p.hostname, b"fe80::822a:a8ff:fe49:470c%tESt")
self.assertEqual(p.netloc, b'[FE80::822a:a8ff:fe49:470c%tESt]:1234')

def test_urlsplit_prevents_hostname_injection(self):
cases = [
# bpo-36338: Ensure that [ is at position 0 of hostname
'http://good.com[bad.com]',
b'http://good.com[bad.com]',
]
for case in cases:
with self.assertRaises(ValueError, msg=case):
urllib.parse.urlsplit(case)

with self.assertRaises(ValueError, msg=case):
urllib.parse.urlparse(case)

def test_urlsplit_attributes(self):
url = "HTTP://WWW.PYTHON.ORG/doc/#frag"
p = urllib.parse.urlsplit(url)
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3 changes: 2 additions & 1 deletion Lib/urllib/parse.py
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Expand Up @@ -436,7 +436,8 @@ def urlsplit(url, scheme='', allow_fragments=True):
if url[:2] == '//':
netloc, url = _splitnetloc(url, 2)
if (('[' in netloc and ']' not in netloc) or
(']' in netloc and '[' not in netloc)):
(']' in netloc and '[' not in netloc) or
('[' in netloc and netloc.index('[') != 0)):
raise ValueError("Invalid IPv6 URL")
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@vstinner vstinner Oct 14, 2019

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_splitnetloc() is called 2 times and the same code to validate the IPv6 address is duplicated, whereas you only fix one place. IMHO it would be better to move the check into _splitnetloc().

if allow_fragments and '#' in url:
url, fragment = url.split('#', 1)
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Security/2019-07-22-13-33-37.bpo-36338.MJll68.rst
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@@ -0,0 +1 @@
Raise ValueError when parsing hostname with ``[`` in position > 0, e.g. ``good.com[malicious.com]``, that would otherwise return a hostname of ``malicious.com``.