https://github.com/python/cpython/commit/95746b3a13a985787ef53b977129041971ed7f70 commit: 95746b3a13a985787ef53b977129041971ed7f70 branch: main author: Seth Michael Larson <[email protected]> committer: sethmlarson <[email protected]> date: 2026-01-20T21:23:42Z summary:
gh-143919: Reject control characters in http cookies Co-authored-by: Bartosz Sławecki <[email protected]> Co-authored-by: sobolevn <[email protected]> files: A Misc/NEWS.d/next/Security/2026-01-16-11-13-15.gh-issue-143919.kchwZV.rst M Doc/library/http.cookies.rst M Lib/http/cookies.py M Lib/test/test_http_cookies.py diff --git a/Doc/library/http.cookies.rst b/Doc/library/http.cookies.rst index 88e978d7f5eafb..50b65459d2f699 100644 --- a/Doc/library/http.cookies.rst +++ b/Doc/library/http.cookies.rst @@ -294,9 +294,9 @@ The following example demonstrates how to use the :mod:`http.cookies` module. Set-Cookie: chips=ahoy Set-Cookie: vienna=finger >>> C = cookies.SimpleCookie() - >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";') + >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=;";') >>> print(C) - Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;" + Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=;" >>> C = cookies.SimpleCookie() >>> C["oreo"] = "doublestuff" >>> C["oreo"]["path"] = "/" diff --git a/Lib/http/cookies.py b/Lib/http/cookies.py index 74349bb63d66e2..917280037d4dbb 100644 --- a/Lib/http/cookies.py +++ b/Lib/http/cookies.py @@ -87,9 +87,9 @@ such trickeries do not confuse it. >>> C = cookies.SimpleCookie() - >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=\\012;";') + >>> C.load('keebler="E=everybody; L=\\"Loves\\"; fudge=;";') >>> print(C) - Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=\012;" + Set-Cookie: keebler="E=everybody; L=\"Loves\"; fudge=;" Each element of the Cookie also supports all of the RFC 2109 Cookie attributes. Here's an example which sets the Path @@ -170,6 +170,15 @@ class CookieError(Exception): }) _is_legal_key = re.compile('[%s]+' % re.escape(_LegalChars)).fullmatch +_control_character_re = re.compile(r'[\x00-\x1F\x7F]') + + +def _has_control_character(*val): + """Detects control characters within a value. + Supports any type, as header values can be any type. + """ + return any(_control_character_re.search(str(v)) for v in val) + def _quote(str): r"""Quote a string for use in a cookie header. @@ -294,12 +303,16 @@ def __setitem__(self, K, V): K = K.lower() if not K in self._reserved: raise CookieError("Invalid attribute %r" % (K,)) + if _has_control_character(K, V): + raise CookieError(f"Control characters are not allowed in cookies {K!r} {V!r}") dict.__setitem__(self, K, V) def setdefault(self, key, val=None): key = key.lower() if key not in self._reserved: raise CookieError("Invalid attribute %r" % (key,)) + if _has_control_character(key, val): + raise CookieError("Control characters are not allowed in cookies %r %r" % (key, val,)) return dict.setdefault(self, key, val) def __eq__(self, morsel): @@ -335,6 +348,9 @@ def set(self, key, val, coded_val): raise CookieError('Attempt to set a reserved key %r' % (key,)) if not _is_legal_key(key): raise CookieError('Illegal key %r' % (key,)) + if _has_control_character(key, val, coded_val): + raise CookieError( + "Control characters are not allowed in cookies %r %r %r" % (key, val, coded_val,)) # It's a good key, so save it. self._key = key @@ -488,7 +504,10 @@ def output(self, attrs=None, header="Set-Cookie:", sep="\015\012"): result = [] items = sorted(self.items()) for key, value in items: - result.append(value.output(attrs, header)) + value_output = value.output(attrs, header) + if _has_control_character(value_output): + raise CookieError("Control characters are not allowed in cookies") + result.append(value_output) return sep.join(result) __str__ = output diff --git a/Lib/test/test_http_cookies.py b/Lib/test/test_http_cookies.py index c2ed30831b2e0e..7d072d5fd67ca7 100644 --- a/Lib/test/test_http_cookies.py +++ b/Lib/test/test_http_cookies.py @@ -17,10 +17,10 @@ def test_basic(self): 'repr': "<SimpleCookie: chips='ahoy' vienna='finger'>", 'output': 'Set-Cookie: chips=ahoy\nSet-Cookie: vienna=finger'}, - {'data': 'keebler="E=mc2; L=\\"Loves\\"; fudge=\\012;"', - 'dict': {'keebler' : 'E=mc2; L="Loves"; fudge=\012;'}, - 'repr': '''<SimpleCookie: keebler='E=mc2; L="Loves"; fudge=\\n;'>''', - 'output': 'Set-Cookie: keebler="E=mc2; L=\\"Loves\\"; fudge=\\012;"'}, + {'data': 'keebler="E=mc2; L=\\"Loves\\"; fudge=;"', + 'dict': {'keebler' : 'E=mc2; L="Loves"; fudge=;'}, + 'repr': '''<SimpleCookie: keebler='E=mc2; L="Loves"; fudge=;'>''', + 'output': 'Set-Cookie: keebler="E=mc2; L=\\"Loves\\"; fudge=;"'}, # Check illegal cookies that have an '=' char in an unquoted value {'data': 'keebler=E=mc2', @@ -594,6 +594,50 @@ def test_repr(self): r'Set-Cookie: key=coded_val; ' r'expires=\w+, \d+ \w+ \d+ \d+:\d+:\d+ \w+') + def test_control_characters(self): + for c0 in support.control_characters_c0(): + morsel = cookies.Morsel() + + # .__setitem__() + with self.assertRaises(cookies.CookieError): + morsel[c0] = "val" + with self.assertRaises(cookies.CookieError): + morsel["path"] = c0 + + # .setdefault() + with self.assertRaises(cookies.CookieError): + morsel.setdefault("path", c0) + with self.assertRaises(cookies.CookieError): + morsel.setdefault(c0, "val") + + # .set() + with self.assertRaises(cookies.CookieError): + morsel.set(c0, "val", "coded-value") + with self.assertRaises(cookies.CookieError): + morsel.set("path", c0, "coded-value") + with self.assertRaises(cookies.CookieError): + morsel.set("path", "val", c0) + + def test_control_characters_output(self): + # Tests that even if the internals of Morsel are modified + # that a call to .output() has control character safeguards. + for c0 in support.control_characters_c0(): + morsel = cookies.Morsel() + morsel.set("key", "value", "coded-value") + morsel._key = c0 # Override private variable. + cookie = cookies.SimpleCookie() + cookie["cookie"] = morsel + with self.assertRaises(cookies.CookieError): + cookie.output() + + morsel = cookies.Morsel() + morsel.set("key", "value", "coded-value") + morsel._coded_value = c0 # Override private variable. + cookie = cookies.SimpleCookie() + cookie["cookie"] = morsel + with self.assertRaises(cookies.CookieError): + cookie.output() + def load_tests(loader, tests, pattern): tests.addTest(doctest.DocTestSuite(cookies)) diff --git a/Misc/NEWS.d/next/Security/2026-01-16-11-13-15.gh-issue-143919.kchwZV.rst b/Misc/NEWS.d/next/Security/2026-01-16-11-13-15.gh-issue-143919.kchwZV.rst new file mode 100644 index 00000000000000..788c3e4ac2ebf7 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2026-01-16-11-13-15.gh-issue-143919.kchwZV.rst @@ -0,0 +1 @@ +Reject control characters in :class:`http.cookies.Morsel` fields and values. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
