[3.13] gh-74453: Add stronger security warning to os.path.commonprefix

miss-islington · sethmlarson · web-flow · commit 5e888993e42b · 2026-02-03T14:16:28.000Z
gh-74453: Add stronger security warning to os.path.commonprefix (GH-144401) (cherry picked from commit 4e15b8d) Co-authored-by: Seth Michael Larson <seth@python.org>
diff --git a/Doc/library/os.path.rst b/Doc/library/os.path.rst
@@ -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.
 
       ::
 
