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Fix CVE-2020-26116:
https://cve.circl.lu/cve/CVE-2020-26116
https://bugs.python.org/issue39603
Taken from upstream (sans test and NEWS update):
https://github.com/python/cpython/commit/668d321476d974c4f51476b33aaca870272523bf
diff --git a/Lib/http/client.py b/Lib/http/client.py
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -147,6 +147,10 @@
# _is_allowed_url_pchars_re = re.compile(r"^[/!$&'()*+,;=:@%a-zA-Z0-9._~-]+$")
# We are more lenient for assumed real world compatibility purposes.
+# These characters are not allowed within HTTP method names
+# to prevent http header injection.
+_contains_disallowed_method_pchar_re = re.compile('[\x00-\x1f]')
+
# We always set the Content-Length header for these methods because some
# servers will otherwise respond with a 411
_METHODS_EXPECTING_BODY = {'PATCH', 'POST', 'PUT'}
@@ -1087,6 +1091,8 @@ def putrequest(self, method, url, skip_host=False,
else:
raise CannotSendRequest(self.__state)
+ self._validate_method(method)
+
# Save the method for use later in the response phase
self._method = method
@@ -1177,6 +1183,15 @@ def _encode_request(self, request):
# ASCII also helps prevent CVE-2019-9740.
return request.encode('ascii')
+ def _validate_method(self, method):
+ """Validate a method name for putrequest."""
+ # prevent http header injection
+ match = _contains_disallowed_method_pchar_re.search(method)
+ if match:
+ raise ValueError(
+ f"method can't contain control characters. {method!r} "
+ f"(found at least {match.group()!r})")
+
def _validate_path(self, url):
"""Validate a url for putrequest."""
# Prevent CVE-2019-9740.
|