https://github.com/python/cpython/commit/6262704b134db2a4ba12e85ecfbd968534f28b45
commit: 6262704b134db2a4ba12e85ecfbd968534f28b45
branch: main
author: Seth Michael Larson <[email protected]>
committer: sethmlarson <[email protected]>
date: 2026-01-20T20:45:42Z
summary:
gh-143921: Reject control characters in IMAP commands
files:
A Misc/NEWS.d/next/Security/2026-01-16-11-41-06.gh-issue-143921.AeCOor.rst
M Lib/imaplib.py
M Lib/test/test_imaplib.py
diff --git a/Lib/imaplib.py b/Lib/imaplib.py
index 22a0afcd981519..cb3edceae0d9f1 100644
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -129,7 +129,7 @@
# We compile these in _mode_xxx.
_Literal = br'.*{(?P<size>\d+)}$'
_Untagged_status = br'\* (?P<data>\d+) (?P<type>[A-Z-]+)( (?P<data2>.*))?'
-
+_control_chars = re.compile(b'[\x00-\x1F\x7F]')
class IMAP4:
@@ -1105,6 +1105,8 @@ def _command(self, name, *args):
if arg is None: continue
if isinstance(arg, str):
arg = bytes(arg, self._encoding)
+ if _control_chars.search(arg):
+ raise ValueError("Control characters not allowed in commands")
data = data + b' ' + arg
literal = self.literal
diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index 430fa71fa29f59..cb5454b40eccf9 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -657,6 +657,12 @@ def test_unselect(self):
self.assertEqual(data[0], b'Returned to authenticated state.
(Success)')
self.assertEqual(client.state, 'AUTH')
+ def test_control_characters(self):
+ client, _ = self._setup(SimpleIMAPHandler)
+ for c0 in support.control_characters_c0():
+ with self.assertRaises(ValueError):
+ client.login(f'user{c0}', 'pass')
+
# property tests
def test_file_property_should_not_be_accessed(self):
diff --git
a/Misc/NEWS.d/next/Security/2026-01-16-11-41-06.gh-issue-143921.AeCOor.rst
b/Misc/NEWS.d/next/Security/2026-01-16-11-41-06.gh-issue-143921.AeCOor.rst
new file mode 100644
index 00000000000000..4e13fe92bc60fb
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-01-16-11-41-06.gh-issue-143921.AeCOor.rst
@@ -0,0 +1 @@
+Reject control characters in IMAP commands.
_______________________________________________
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]
