From 7a7d2de96b22a9adf9208afcc9547e1001569fef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20Gr=C3=B6nholm?= <alex.gronholm@nextday.fi>
Date: Thu, 22 Jan 2026 01:41:14 +0200
Subject: [PATCH] Fixed security issue around wheel unpack (#675)

A maliciously crafted wheel could cause the permissions of a file outside the unpack tree to be altered.

Fixes CVE-2026-24049.
---
 docs/news.rst                 |  2 ++
 src/wheel/_commands/unpack.py |  4 ++--
 tests/commands/test_unpack.py | 23 +++++++++++++++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

Index: wheel-0.42.0/src/wheel/cli/unpack.py
===================================================================
--- wheel-0.42.0.orig/src/wheel/cli/unpack.py
+++ wheel-0.42.0/src/wheel/cli/unpack.py
@@ -19,12 +19,12 @@ def unpack(path: str, dest: str = ".") -
         destination = Path(dest) / namever
         print(f"Unpacking to: {destination}...", end="", flush=True)
         for zinfo in wf.filelist:
-            wf.extract(zinfo, destination)
+            target_path = Path(wf.extract(zinfo, destination))
 
             # Set permissions to the same values as they were set in the archive
             # We have to do this manually due to
             # https://github.com/python/cpython/issues/59999
             permissions = zinfo.external_attr >> 16 & 0o777
-            destination.joinpath(zinfo.filename).chmod(permissions)
+            target_path.chmod(permissions)
 
     print("OK")
Index: wheel-0.42.0/tests/cli/test_unpack.py
===================================================================
--- wheel-0.42.0.orig/tests/cli/test_unpack.py
+++ wheel-0.42.0/tests/cli/test_unpack.py
@@ -8,6 +8,7 @@ import pytest
 from wheel.cli.unpack import unpack
 from wheel.wheelfile import WheelFile
 
+from .util import run_command
 
 def test_unpack(wheel_paths, tmp_path):
     """
@@ -34,3 +35,26 @@ def test_unpack_executable_bit(tmp_path)
     unpack(str(wheel_path), str(tmp_path))
     assert not script_path.is_dir()
     assert stat.S_IMODE(script_path.stat().st_mode) == 0o755
+
+
+@pytest.mark.skipif(
+    platform.system() == "Windows", reason="Windows does not support chmod()"
+)
+def test_chmod_outside_unpack_tree(tmp_path_factory: TempPathFactory) -> None:
+    wheel_path = tmp_path_factory.mktemp("build") / "test-1.0-py3-none-any.whl"
+    with WheelFile(wheel_path, "w") as wf:
+        wf.writestr(
+            "test-1.0.dist-info/METADATA",
+            "Metadata-Version: 2.4\nName: test\nVersion: 1.0\n",
+        )
+        wf.writestr("../../system-file", b"malicious data")
+
+    extract_root_path = tmp_path_factory.mktemp("extract")
+    system_file = extract_root_path / "system-file"
+    extract_path = extract_root_path / "subdir"
+    system_file.write_bytes(b"important data")
+    system_file.chmod(0o755)
+    run_command("unpack", "--dest", extract_path, wheel_path)
+
+    assert system_file.read_bytes() == b"important data"
+    assert stat.S_IMODE(system_file.stat().st_mode) == 0o755
Index: wheel-0.42.0/tests/cli/util.py
===================================================================
--- /dev/null
+++ wheel-0.42.0/tests/cli/util.py
@@ -0,0 +1,43 @@
+from __future__ import annotations
+
+import sys
+from io import StringIO
+from os import PathLike
+from subprocess import CalledProcessError
+from unittest.mock import patch
+
+import pytest
+
+from wheel.cli import main
+
+
+def run_command(
+    command: str, *args: str | PathLike, catch_systemexit: bool = True
+) -> str:
+    returncode = 0
+    stdout = StringIO()
+    stderr = StringIO()
+    args = ("wheel", command) + tuple(str(arg) for arg in args)
+    with (
+        patch.object(sys, "argv", args),
+        patch.object(sys, "stdout", stdout),
+        patch.object(sys, "stderr", stderr),
+    ):
+        try:
+            main()
+        except SystemExit as exc:
+            if not catch_systemexit:
+                raise CalledProcessError(
+                    exc.code, args, stdout.getvalue(), stderr.getvalue()
+                ) from exc
+
+            returncode = exc.code
+
+    if returncode:
+        pytest.fail(
+            f"'wheel {command}' exited with return code {returncode}\n"
+            f"arguments: {args}\n"
+            f"error output:\n{stderr.getvalue()}"
+        )
+
+    return stdout.getvalue()
Index: wheel-0.42.0/tests/cli/__init__.py
===================================================================
--- /dev/null
+++ wheel-0.42.0/tests/cli/__init__.py
@@ -0,0 +1 @@
+