gh-160322: Refuse symlinks with a trailing separator in shutil.rmtree()

Doc/library/shutil.rst

@@ -311,7 +311,8 @@ Directory and files operations
    .. index:: single: directory; deleting
 
    Delete an entire directory tree; *path* must point to a directory (but not a
-   symbolic link to a directory).  If *ignore_errors* is true, errors resulting
+   symbolic link to a directory, with or without a trailing path separator).
+   If *ignore_errors* is true, errors resulting
    from failed removals will be ignored; if false or omitted, such errors are
    handled by calling a handler specified by *onexc* or *onerror* or, if both
    are omitted, exceptions are propagated to the caller.
@@ -367,6 +368,12 @@ Directory and files operations
       Exceptions other than :exc:`OSError` and subclasses of :exc:`!OSError`
       are now always propagated to the caller.
 
+   .. versionchanged:: next
+      A symbolic link to a directory is now also refused when *path* has a
+      trailing path separator, instead of deleting the contents of the
+      directory it points to.  Error handlers receive *path* without
+      trailing separators.
+
    .. attribute:: rmtree.avoids_symlink_attacks
 
       Indicates whether the current platform and implementation provides a

Lib/shutil.py

@@ -847,6 +847,16 @@ def rmtree(path, ignore_errors=False, onerror=None, *, onexc=None, dir_fd=None,
     """
 
     sys.audit("shutil.rmtree", path, dir_fd)
+    # Strip trailing separators: "link/" names the target of a symlink, which
+    # would defeat the symlink check and delete the target's contents.
+    fspath = os.fspath(path)
+    drive, root, tail = os.path.splitroot(fspath)
+    seps = os.sep + (os.altsep or '')
+    if isinstance(fspath, bytes):
+        seps = os.fsencode(seps)
+    stripped = tail.rstrip(seps)
+    if stripped != tail:
+        path = drive + root + stripped
     if ignore_errors:
         def onexc(*args, **kwargs):
             pass

Lib/test/test_shutil.py

@@ -232,6 +232,42 @@ def onexc(*args):
         self.assertEqual(errors[0][1], link)
         self.assertIsInstance(errors[0][2], OSError)
 
+    @os_helper.skip_unless_symlink
+    def test_rmtree_fails_on_symlink_with_trailing_sep(self):
+        tmp = self.mkdtemp()
+        dir_ = os.path.join(tmp, 'dir')
+        os.mkdir(dir_)
+        create_file(os.path.join(dir_, 'file'), 'foo')
+        link = os.path.join(tmp, 'link')
+        os.symlink(dir_, link)
+        for path in (link + os.sep, link + os.sep * 2,
+                     os.fsencode(link + os.sep)):
+            with self.subTest(path=path):
+                self.assertRaises(OSError, shutil.rmtree, path)
+                self.assertTrue(os.path.exists(os.path.join(dir_, 'file')))
+                self.assertTrue(os.path.lexists(link))
+        errors = []
+        def onexc(*args):
+            errors.append(args)
+        shutil.rmtree(link + os.sep, onexc=onexc)
+        self.assertEqual(len(errors), 1)
+        self.assertIs(errors[0][0], os.path.islink)
+        self.assertEqual(errors[0][1], link)
+        self.assertIsInstance(errors[0][2], OSError)
+        self.assertTrue(os.path.exists(os.path.join(dir_, 'file')))
+
+    def test_rmtree_works_with_trailing_sep(self):
+        tmp = self.mkdtemp()
+        victim = os.path.join(tmp, 'killme')
+        os.mkdir(victim)
+        create_file(os.path.join(victim, 'somefile'), 'foo')
+        shutil.rmtree(victim + os.sep)
+        self.assertFalse(os.path.lexists(victim))
+        os.mkdir(victim)
+        create_file(os.path.join(victim, 'somefile'), 'foo')
+        shutil.rmtree(os.fsencode(victim + os.sep * 2))
+        self.assertFalse(os.path.lexists(victim))
+
     @os_helper.skip_unless_symlink
     def test_rmtree_works_on_symlinks(self):
         tmp = self.mkdtemp()

Misc/NEWS.d/next/Library/2026-10-22-08-15-35.gh-issue-160322.rT4slk.rst

@@ -0,0 +1,3 @@
+Fix :func:`shutil.rmtree` deleting the contents of the target directory when
+given a symbolic link to a directory with a trailing path separator.  It now
+fails like it does for the link without the separator.