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gh-74453: Add stronger security warning to os.path.commonprefix #144401

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Merged
encukou merged 3 commits into from
Feb 3, 2026
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gh-74453: Add stronger security warning to os.path.commonprefix #144401

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5704727
Add stronger security warning to os.path.commonprefix
sethmlarson Feb 2, 2026
fa43ff8
Remove duplicated recommendation to use `commonpath()`.
sethmlarson Feb 2, 2026
79e135c
Use "warning", not "danger"
sethmlarson Feb 2, 2026
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12 changes: 7 additions & 5 deletions Doc/library/os.path.rst
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Expand Up @@ -97,15 +97,17 @@ the :mod:`glob` module.)

.. function:: commonprefix(list, /)

Return the longest path prefix (taken character-by-character) that is a
prefix of all paths in *list*. If *list* is empty, return the empty string
Return the longest string prefix (taken character-by-character) that is a
prefix of all strings in *list*. If *list* is empty, return the empty string
(``''``).

.. note::
.. warning::

This function may return invalid paths because it works a
character at a time. To obtain a valid path, see
:func:`commonpath`.
character at a time.
If you need a **common path prefix**, then the algorithm
implemented in this function is not secure. Use
:func:`commonpath` for finding a common path prefix.

::

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