File CVE-2026-0672-http-hdr-inject-cookie-Morsel.patch of Package python310
From 57c5ecd7e61fbb24e7de76eafd95332bd0ae4dea Mon Sep 17 00:00:00 2001
From: Seth Michael Larson <seth@python.org>
Date: Tue, 20 Jan 2026 15:23:42 -0600
Subject: [PATCH] [3.10] gh-143919: Reject control characters in http cookies
(cherry picked from commit 95746b3a13a985787ef53b977129041971ed7f70)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Co-authored-by: Seth Michael Larson <seth@python.org>
Co-authored-by: Bartosz Sławecki <bartosz@ilikepython.com>
Co-authored-by: sobolevn <mail@sobolevn.me>
---
Doc/library/http.cookies.rst | 4 +-
Lib/http/cookies.py | 25 +++++++--
Lib/test/test_http_cookies.py | 52 +++++++++++++++++--
...-01-16-11-13-15.gh-issue-143919.kchwZV.rst | 1 +
4 files changed, 73 insertions(+), 9 deletions(-)
create mode 100644 Misc/NEWS.d/next/Security/2026-01-16-11-13-15.gh-issue-143919.kchwZV.rst
diff --git a/Doc/library/http.cookies.rst b/Doc/library/http.cookies.rst
index a2c1eb00d8b33d..4cb563c230ea5e 100644
--- a/Doc/library/http.cookies.rst
+++ b/Doc/library/http.cookies.rst
@@ -270,9 +270,9 @@ 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 2c1f021d0abede..5cfa7a8072c7f7 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.
@@ -292,12 +301,16 @@ 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):
@@ -333,6 +346,9 @@ 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
@@ -484,7 +500,10 @@ 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 644e75cd5b742e..1f2c049fa811fa 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',
@@ -517,6 +517,50 @@ 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 test_main():
run_unittest(CookieTests, MorselTests)
run_doctest(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.
