3.14.4: CVE-2026-1502, CVE-2026-4786, CVE-2026-5713, CVE-2026-6100

Lib/http/client.py

@@ -972,13 +972,22 @@ def _wrap_ipv6(self, ip):
         return ip
 
     def _tunnel(self):
+        if _contains_disallowed_url_pchar_re.search(self._tunnel_host):
+            raise ValueError('Tunnel host can\'t contain control characters %r'
+                             % (self._tunnel_host,))
         connect = b"CONNECT %s:%d %s\r\n" % (
             self._wrap_ipv6(self._tunnel_host.encode("idna")),
             self._tunnel_port,
             self._http_vsn_str.encode("ascii"))
         headers = [connect]
         for header, value in self._tunnel_headers.items():
-            headers.append(f"{header}: {value}\r\n".encode("latin-1"))
+            header_bytes = header.encode("latin-1")
+            value_bytes = value.encode("latin-1")
+            if not _is_legal_header_name(header_bytes):
+                raise ValueError('Invalid header name %r' % (header_bytes,))
+            if _is_illegal_header_value(value_bytes):
+                raise ValueError('Invalid header value %r' % (value_bytes,))
+            headers.append(b"%s: %s\r\n" % (header_bytes, value_bytes))
         headers.append(b"\r\n")
         # Making a single send() call instead of one per line encourages
         # the host OS to use a more optimal packet size instead of

Lib/test/test_httplib.py

@@ -369,6 +369,51 @@ def test_invalid_headers(self):
                 with self.assertRaisesRegex(ValueError, 'Invalid header'):
                     conn.putheader(name, value)
 
+    def test_invalid_tunnel_headers(self):
+        cases = (
+            ('Invalid\r\nName', 'ValidValue'),
+            ('Invalid\rName', 'ValidValue'),
+            ('Invalid\nName', 'ValidValue'),
+            ('\r\nInvalidName', 'ValidValue'),
+            ('\rInvalidName', 'ValidValue'),
+            ('\nInvalidName', 'ValidValue'),
+            (' InvalidName', 'ValidValue'),
+            ('\tInvalidName', 'ValidValue'),
+            ('Invalid:Name', 'ValidValue'),
+            (':InvalidName', 'ValidValue'),
+            ('ValidName', 'Invalid\r\nValue'),
+            ('ValidName', 'Invalid\rValue'),
+            ('ValidName', 'Invalid\nValue'),
+            ('ValidName', 'InvalidValue\r\n'),
+            ('ValidName', 'InvalidValue\r'),
+            ('ValidName', 'InvalidValue\n'),
+        )
+        for name, value in cases:
+            with self.subTest((name, value)):
+                conn = client.HTTPConnection('example.com')
+                conn.set_tunnel('tunnel', headers={
+                    name: value
+                })
+                conn.sock = FakeSocket('')
+                with self.assertRaisesRegex(ValueError, 'Invalid header'):
+                    conn._tunnel()  # Called in .connect()
+
+    def test_invalid_tunnel_host(self):
+        cases = (
+            'invalid\r.host',
+            '\ninvalid.host',
+            'invalid.host\r\n',
+            'invalid.host\x00',
+            'invalid host',
+        )
+        for tunnel_host in cases:
+            with self.subTest(tunnel_host):
+                conn = client.HTTPConnection('example.com')
+                conn.set_tunnel(tunnel_host)
+                conn.sock = FakeSocket('')
+                with self.assertRaisesRegex(ValueError, 'Tunnel host can\'t contain control characters'):
+                    conn._tunnel()  # Called in .connect()
+
     def test_headers_debuglevel(self):
         body = (
             b'HTTP/1.1 200 OK\r\n'

Lib/test/test_webbrowser.py

@@ -119,6 +119,15 @@ def test_open_bad_new_parameter(self):
                        arguments=[URL],
                        kw=dict(new=999))
 
+    def test_reject_action_dash_prefixes(self):
+        browser = self.browser_class(name=CMD_NAME)
+        with self.assertRaises(ValueError):
+            browser.open('%action--incognito')
+        # new=1: action is "--new-window", so "%action" itself expands to
+        # a dash-prefixed flag even with no dash in the original URL.
+        with self.assertRaises(ValueError):
+            browser.open('%action', new=1)
+
 
 class EdgeCommandTest(CommandTestMixin, unittest.TestCase):
 

Lib/webbrowser.py

@@ -274,7 +274,6 @@ def _invoke(self, args, remote, autoraise, url=None):
 
     def open(self, url, new=0, autoraise=True):
         sys.audit("webbrowser.open", url)
-        self._check_url(url)
         if new == 0:
             action = self.remote_action
         elif new == 1:
@@ -288,7 +287,9 @@ def open(self, url, new=0, autoraise=True):
             raise Error("Bad 'new' parameter to open(); "
                         f"expected 0, 1, or 2, got {new}")
 
-        args = [arg.replace("%s", url).replace("%action", action)
+        self._check_url(url.replace("%action", action))
+
+        args = [arg.replace("%action", action).replace("%s", url)
                 for arg in self.remote_args]
         args = [arg for arg in args if arg]
         success = self._invoke(args, True, autoraise, url)

Misc/NEWS.d/next/Security/2026-03-20-09-29-42.gh-issue-146211.PQVbs7.rst

@@ -0,0 +1,2 @@
+Reject CR/LF characters in tunnel request headers for the
+HTTPConnection.set_tunnel() method.

Misc/NEWS.d/next/Security/2026-03-31-09-15-51.gh-issue-148169.EZJzz2.rst

@@ -0,0 +1,2 @@
+A bypass in :mod:`webbrowser` allowed URLs prefixed with ``%action`` to pass
+the dash-prefix safety check.

Misc/NEWS.d/next/Security/2026-04-06-13-55-00.gh-issue-148178.Rs7kLm.rst

@@ -0,0 +1,2 @@
+Hardened :mod:`!_remote_debugging` by validating remote debug offset tables
+before using them to size memory reads or interpret remote layouts.

Misc/NEWS.d/next/Security/2026-04-10-16-28-21.gh-issue-148395.kfzm0G.rst

@@ -0,0 +1,5 @@
+Fix a dangling input pointer in :class:`lzma.LZMADecompressor`,
+:class:`bz2.BZ2Decompressor`, and internal :class:`!zlib._ZlibDecompressor`
+when memory allocation fails with :exc:`MemoryError`, which could let a
+subsequent :meth:`!decompress` call read or write through a stale pointer to
+the already-released caller buffer.

Modules/_bz2module.c

@@ -593,6 +593,7 @@ decompress(BZ2Decompressor *d, char *data, size_t len, Py_ssize_t max_length)
     return result;
 
 error:
+    bzs->next_in = NULL;
     Py_XDECREF(result);
     return NULL;
 }

Modules/_lzmamodule.c

@@ -1120,6 +1120,7 @@ decompress(Decompressor *d, uint8_t *data, size_t len, Py_ssize_t max_length)
     return result;
 
 error:
+    lzs->next_in = NULL;
     Py_XDECREF(result);
     return NULL;
 }