From dba24a5eeb065d5ac552b3049d2cc99c0bda13fb Mon Sep 17 00:00:00 2001
From: Damian Shaw <damian.peter.shaw@gmail.com>
Date: Wed, 20 May 2026 15:20:25 -0400
Subject: [PATCH] Reject entry point names that escape scripts dir (#14000)

* Reject entry point names that escape scripts dir

* NEWS ENTRY
---
 news/14000.bugfix.rst                         |  2 +
 src/pip/_internal/operations/install/wheel.py | 26 +++++++-
 tests/unit/test_wheel.py                      | 64 +++++++++++++++++++
 2 files changed, 87 insertions(+), 3 deletions(-)

diff --git a/src/pip/_internal/operations/install/wheel.py b/src/pip/_internal/operations/install/wheel.py
index 2724f150f..ec2faaa5d 100644
--- a/src/pip/_internal/operations/install/wheel.py
+++ b/src/pip/_internal/operations/install/wheel.py
@@ -397,11 +397,31 @@ class MissingCallableSuffix(InstallationError):
         )
 
 
-def _raise_for_invalid_entrypoint(specification: str) -> None:
+def _script_within_dir(name: str, scripts_dir: str) -> bool:
+    """Return whether script ``name`` resolves to a path inside the ``scripts_dir``.
+
+    distlib joins the entry point name onto the scripts directory, so a name
+    with path separators or ``..`` components can resolve elsewhere.
+    """
+    root = os.path.normpath(scripts_dir)
+    dest = os.path.normpath(os.path.join(scripts_dir, name))
+    return dest.startswith(root + os.sep)
+
+
+def _raise_for_invalid_entrypoint(specification: str, scripts_dir: str) -> None:
     entry = get_export_entry(specification)
-    if entry is not None and entry.suffix is None:
+    if entry is None:
+        return
+
+    if entry.suffix is None:
         raise MissingCallableSuffix(str(entry))
 
+    if not _script_within_dir(entry.name, scripts_dir):
+        raise InstallationError(
+            f"Invalid script entry point name {entry.name!r}: the script "
+            f"would be installed outside the scripts directory ({scripts_dir})."
+        )
+
 
 class PipScriptMaker(ScriptMaker):
     # Override distlib's default script template with one that
@@ -420,7 +440,7 @@ class PipScriptMaker(ScriptMaker):
     def make(
         self, specification: str, options: dict[str, Any] | None = None
     ) -> list[str]:
-        _raise_for_invalid_entrypoint(specification)
+        _raise_for_invalid_entrypoint(specification, self.target_dir)
         return super().make(specification, options)
 
 
diff --git a/tests/unit/test_wheel.py b/tests/unit/test_wheel.py
index 028ad3a46..bce0607ec 100644
--- a/tests/unit/test_wheel.py
+++ b/tests/unit/test_wheel.py
@@ -519,6 +519,32 @@ class TestInstallUnpackedWheel:
         assert os.path.basename(wheel_path) in exc_text
         assert entrypoint in exc_text
 
+    @pytest.mark.parametrize("bad_name", ["../../outside", "..", "."])
+    @pytest.mark.parametrize("entry_point_type", ["console_scripts", "gui_scripts"])
+    def test_wheel_install_rejects_entry_point_path_traversal(
+        self, data: TestData, tmpdir: Path, bad_name: str, entry_point_type: str
+    ) -> None:
+        """An entry point name with separators or ``..`` must not install a
+        script outside the scripts directory.
+        """
+        self.prep(data, tmpdir)
+        wheel_path = make_wheel(
+            "simple",
+            "0.1.0",
+            entry_points={entry_point_type: [f"{bad_name} = simple:main"]},
+        ).save_to_dir(tmpdir)
+        with pytest.raises(InstallationError) as e:
+            wheel.install_wheel(
+                "simple",
+                str(wheel_path),
+                scheme=self.scheme,
+                req_description="simple",
+            )
+
+        assert "outside the scripts directory" in str(e.value)
+        # Nothing was written outside the install destination.
+        assert not os.path.exists(os.path.join(str(tmpdir), "outside"))
+
 
 class TestMessageAboutScriptsNotOnPATH:
     tilde_warning_msg = (
@@ -722,3 +748,41 @@ def test_get_console_script_specs_replaces_python_version(
         "not_pip_or_easy_install-99 = whatever",
         "not_pip_or_easy_install-99.88 = whatever",
     ]
+
+
+@pytest.mark.parametrize(
+    "name, within",
+    [
+        ("pip", True),
+        ("pip3.13", True),
+        ("foo-bar.baz", True),
+        ("...", True),  # a literal filename, not a path component
+        ("sub/script", True),  # in-tree subdirectory
+        ("a/../b", True),
+        ("sub\\script", True),  # backslash stays in-tree on POSIX and Windows
+        (" ../../inside", True),  # distlib keeps a leading space; resolves in-tree
+        ("../outside", False),
+        ("../../outside", False),
+        ("a/../../outside", False),
+        ("/etc/cron.d/outside", False),  # absolute path; os.path.join drops the root
+        # "." and ".." pass PyPI's [\w.-]+ name check but must be rejected here.
+        (".", False),
+        ("..", False),
+        ("", False),
+    ],
+)
+def test_script_within_dir(name: str, within: bool) -> None:
+    assert wheel._script_within_dir(name, "/srv/env/bin") is within
+
+
+def test_script_within_dir_allows_doubled_slash_root() -> None:
+    # A scripts directory can have a doubled leading slash
+    assert wheel._script_within_dir("pip", "//srv/env/bin") is True
+    assert wheel._script_within_dir("../outside", "//srv/env/bin") is False
+
+
+@pytest.mark.skipif(not WINDOWS, reason="drive letters only matter on Windows")
+def test_script_within_dir_rejects_other_drive() -> None:
+    # Validate that a script on a different drive is rejected,
+    # and doesn't throw an error
+    assert wheel._script_within_dir("D:\\outside", "C:\\env\\bin") is False