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gh-150751: validate http.client Content-Length and chunk-size by metsw24-max · Pull Request #150752 · python/cpython · GitHub
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gh-150751: validate http.client Content-Length and chunk-size #150752

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Merged
encukou merged 2 commits into from
Oct 8, 2026
+42 −8
Merged

gh-150751: validate http.client Content-Length and chunk-size #150752

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ae7724a
gh-150751: validate http.client Content-Length and chunk-size
metsw24-max Jun 2, 2026
9a1b068
Shorten the grammar comment and only rstrip the chunk-size line
metsw24-max Oct 7, 2026
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Shorten the grammar comment and only rstrip the chunk-size line
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@metsw24-max
metsw24-max committed Oct 7, 2026
commit 9a1b068ec9891441629ff54f8a7538e7b51a1d3e
8 changes: 3 additions & 5 deletions Lib/http/client.py
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Original file line number Diff line number Diff line change
Expand Up @@ -158,10 +158,8 @@
# to prevent http header injection.
_contains_disallowed_method_pchar_re = re.compile('[\x00-\x1f]')

# RFC 9112: Content-Length = 1*DIGIT and chunk-size = 1*HEXDIG. int() is more
# permissive (it accepts a leading sign, underscores, surrounding whitespace
# and, in base 16, an "0x" prefix and non-ASCII digits), so the body-framing
# values are matched against the grammar before being passed to int().
# RFC 9112: Content-Length = 1*DIGIT and chunk-size = 1*HEXDIG.
# int() is more permissive, so we match against the grammar before calling it.
_is_legal_content_length = re.compile(r'[0-9]+').fullmatch
_is_legal_chunk_size = re.compile(rb'[0-9a-fA-F]+').fullmatch

Expand Down Expand Up @@ -551,7 +549,7 @@ def _read_next_chunk_size(self):
i = line.find(b";")
if i >= 0:
line = line[:i] # strip chunk-extensions
line = line.strip()
line = line.rstrip()
try:
if not _is_legal_chunk_size(line):
raise ValueError("invalid chunk size")
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5 changes: 3 additions & 2 deletions Lib/test/test_httplib.py
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Expand Up @@ -1334,9 +1334,10 @@ def test_malformed_content_length(self):

def test_malformed_chunk_size(self):
# RFC 9112: chunk-size = 1*HEXDIG. Reject sizes that int(_, 16) accepts
# but the grammar forbids (a sign, an "0x" prefix or underscores).
# but the grammar forbids (a sign, an "0x" prefix, underscores or
# leading whitespace).
start = 'HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked\r\n\r\n'
for size in ('-5', '+5', '0x5', '1_f'):
for size in ('-5', '+5', '0x5', '1_f', ' 5'):
with self.subTest(size=size):
sock = FakeSocket(start + '%s\r\nHELLO\r\n0\r\n\r\n' % size)
resp = client.HTTPResponse(sock, method="GET")
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