From f03a28faa66c633feca755617289abeb5d8bbc04 Mon Sep 17 00:00:00 2001 From: Steve Dower Date: Wed, 17 Apr 2024 19:32:47 +0100 Subject: [PATCH] gh-114539: Clarify implicit launching of shells by subprocess (GH-117996) (cherry picked from commit a4b44d39cd6941cc03590fee7538776728bdfd0a) Co-authored-by: Steve Dower --- Doc/library/subprocess.rst | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst index fc66663546b982..7eb9f3042405ff 100644 --- a/Doc/library/subprocess.rst +++ b/Doc/library/subprocess.rst @@ -741,8 +741,8 @@ Exceptions defined in this module all inherit from :exc:`SubprocessError`. Security Considerations ----------------------- -Unlike some other popen functions, this implementation will never -implicitly call a system shell. This means that all characters, +Unlike some other popen functions, this library will not +implicitly choose to call a system shell. This means that all characters, including shell metacharacters, can safely be passed to child processes. If the shell is invoked explicitly, via ``shell=True``, it is the application's responsibility to ensure that all whitespace and metacharacters are @@ -751,6 +751,14 @@ quoted appropriately to avoid vulnerabilities. On :ref:`some platforms `, it is possible to use :func:`shlex.quote` for this escaping. +On Windows, batch files (:file:`*.bat` or :file:`*.cmd`) may be launched by the +operating system in a system shell regardless of the arguments passed to this +library. This could result in arguments being parsed according to shell rules, +but without any escaping added by Python. If you are intentionally launching a +batch file with arguments from untrusted sources, consider passing +``shell=True`` to allow Python to escape special characters. See :gh:`114539` +for additional discussion. + Popen Objects -------------