Fix CVE-2023-24816 by removing legacy code.

Remove legacy code that might trigger a CVE.

Currently set_term_title is only called with (semi-)trusted input that
contain the current working directory of the current IPython session. If
an attacker can control directory names, and manage to get a user cd
into this directory the attacker can execute arbitrary commands
contained in the folder names.

Example:

    - On a windows machine where python is built without _ctypes, create
      a folder called && echo "pwn" > pwn.txt. This can be done by for
      example cloning a git repository.
    - call toggled_set_term_title(True), (or have the preference to
      true)
    - Open IPython and cd into this directory.
    - the folder now contain a pwn.txt, with pwn as content, despite the
      user not asking for any code execution.

Workaround:

    Set the configuration option
    c.TerminalInteractiveShell.term_title_format='IPython' (or to any
    other fixed, safe string).

IPython/__init__.py

@@ -63,7 +63,7 b' __version__ = release.version'
 version_info = release.version_info
 # list of CVEs that should have been patched in this release.
 # this is informational and should not be relied upon.
-__patched_cves__ = {"CVE-2022-21699"}
+__patched_cves__ = {"CVE-2022-21699", "CVE-2023-24816"}
 
 
 def embed_kernel(module=None, local_ns=None, **kwargs):

IPython/utils/terminal.py

@@ -91,7 +91,6 b" if os.name == 'posix':"
         _set_term_title = _set_term_title_xterm
         _restore_term_title = _restore_term_title_xterm
 elif sys.platform == 'win32':
-    try:
         import ctypes
 
         SetConsoleTitleW = ctypes.windll.kernel32.SetConsoleTitleW
@@ -100,21 +99,6 b" elif sys.platform == 'win32':"
         def _set_term_title(title):
             """Set terminal title using ctypes to access the Win32 APIs."""
             SetConsoleTitleW(title)
-    except ImportError:
-        def _set_term_title(title):
-            """Set terminal title using the 'title' command."""
-            global ignore_termtitle
-
-            try:
-                # Cannot be on network share when issuing system commands
-                curr = os.getcwd()
-                os.chdir("C:")
-                ret = os.system("title " + title)
-            finally:
-                os.chdir(curr)
-            if ret:
-                # non-zero return code signals error, don't try again
-                ignore_termtitle = True
 
 
 def set_term_title(title):

docs/source/whatsnew/version8.rst

@@ -2,6 +2,18 b''
  8.x Series
 ============
 
+
+IPython 8.9.1
+-------------
+
+Out of schedule release of IPython with minor fixes to patch a potential CVE-2023-24816.
+This is a really low severity CVE that you most likely are not affected by unless:
+
+ - You are on windows.
+ - You have a custom build of Python without ``_ctypes``
+ - You cd or start IPython or Jupyter in untrusted directory which names may be valid shell commands.
+
+
 .. _version 8.9.0:
 
 IPython 8.9.0