https://github.com/python/cpython/commit/b234a2b67539f787e191d2ef19a7cbdce32874e7
commit: b234a2b67539f787e191d2ef19a7cbdce32874e7
branch: main
author: Seth Michael Larson <[email protected]>
committer: sethmlarson <[email protected]>
date: 2026-01-20T20:46:32Z
summary:
gh-143923: Reject control characters in POP3 commands
files:
A Misc/NEWS.d/next/Security/2026-01-16-11-43-47.gh-issue-143923.DuytMe.rst
M Lib/poplib.py
M Lib/test/test_poplib.py
diff --git a/Lib/poplib.py b/Lib/poplib.py
index 4469bff44b4c45..b97274c5c32ee6 100644
--- a/Lib/poplib.py
+++ b/Lib/poplib.py
@@ -122,6 +122,8 @@ def _putline(self, line):
def _putcmd(self, line):
if self._debugging: print('*cmd*', repr(line))
line = bytes(line, self.encoding)
+ if re.search(b'[\x00-\x1F\x7F]', line):
+ raise ValueError('Control characters not allowed in commands')
self._putline(line)
diff --git a/Lib/test/test_poplib.py b/Lib/test/test_poplib.py
index ef2da97f86734a..18ca7cb556836e 100644
--- a/Lib/test/test_poplib.py
+++ b/Lib/test/test_poplib.py
@@ -17,6 +17,7 @@
from test.support import threading_helper
from test.support import asynchat
from test.support import asyncore
+from test.support import control_characters_c0
test_support.requires_working_socket(module=True)
@@ -395,6 +396,13 @@ def test_quit(self):
self.assertIsNone(self.client.sock)
self.assertIsNone(self.client.file)
+ def test_control_characters(self):
+ for c0 in control_characters_c0():
+ with self.assertRaises(ValueError):
+ self.client.user(f'user{c0}')
+ with self.assertRaises(ValueError):
+ self.client.pass_(f'{c0}pass')
+
@requires_ssl
def test_stls_capa(self):
capa = self.client.capa()
diff --git
a/Misc/NEWS.d/next/Security/2026-01-16-11-43-47.gh-issue-143923.DuytMe.rst
b/Misc/NEWS.d/next/Security/2026-01-16-11-43-47.gh-issue-143923.DuytMe.rst
new file mode 100644
index 00000000000000..3cde4df3e0069f
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-01-16-11-43-47.gh-issue-143923.DuytMe.rst
@@ -0,0 +1 @@
+Reject control characters in POP3 commands.
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