[3.12] gh-146581: Fix vulnerability in shutil.unpack_archive() for ZIP files on Windows (GH-146591) (#149066)
Yhg1s <[email protected]> Tue, 04 Aug 2026 05:21:05 -0400 (EDT)
| Newsgroups | gmane.comp.python.cvs |
|---|---|
| Message-ID | <[email protected]> |
https://github.com/python/cpython/commit/a6650a2cdf0c49fb8ce0c982903aa2aa274beefe commit: a6650a2cdf0c49fb8ce0c982903aa2aa274beefe branch: 3.12 author: Miss Islington (bot) <[email protected]> committer: Yhg1s <[email protected]> date: 2026-08-04T11:20:47+02:00 summary: [3.12] gh-146581: Fix vulnerability in shutil.unpack_archive() for ZIP files on Windows (GH-146591) (#149066) gh-146581: Fix vulnerability in shutil.unpack_archive() for ZIP files on Windows (GH-146591) Use ZipFile.extractall() to sanitize file names and extract files. Files with invalid names (e.g. absolute paths) are now skipped. Files containing ".." in the name are no longer skipped. (cherry picked from commit fc829e88753858c8ac669594bf0093f44948c0f4) Co-authored-by: Serhiy Storchaka <[email protected]> files: A Misc/NEWS.d/next/Security/2026-03-29-12-51-33.gh-issue-146581.4vZfB0.rst M Lib/shutil.py M Lib/test/test_shutil.py M Lib/zipfile/__init__.py diff --git a/Lib/shutil.py b/Lib/shutil.py index 2d2856912893bd1..90f6c024afe332d 100644 --- a/Lib/shutil.py +++ b/Lib/shutil.py @@ -1237,27 +1237,9 @@ def _unpack_zipfile(filename, extract_dir): if not zipfile.is_zipfile(filename): raise ReadError("%s is not a zip file" % filename) - zip = zipfile.ZipFile(filename) - try: - for info in zip.infolist(): - name = info.filename - - # don't extract absolute paths or ones with .. in them - if name.startswith('/') or '..' in name: - continue - - targetpath = os.path.join(extract_dir, *name.split('/')) - if not targetpath: - continue - - _ensure_directory(targetpath) - if not name.endswith('/'): - # file - with zip.open(name, 'r') as source, \ - open(targetpath, 'wb') as target: - copyfileobj(source, target) - finally: - zip.close() + with zipfile.ZipFile(filename) as zip: + zip._ignore_invalid_names = True + zip.extractall(extract_dir) def _unpack_tarfile(filename, extract_dir, *, filter=None): """Unpack tar/tar.gz/tar.bz2/tar.xz `filename` to `extract_dir` diff --git a/Lib/test/test_shutil.py b/Lib/test/test_shutil.py index 669f6a28781a509..b7be547de412e1b 100644 --- a/Lib/test/test_shutil.py +++ b/Lib/test/test_shutil.py @@ -2059,8 +2059,6 @@ def test_make_zipfile_rootdir_nodir(self): def check_unpack_archive(self, format, **kwargs): self.check_unpack_archive_with_converter( format, lambda path: path, **kwargs) - self.check_unpack_archive_with_converter( - format, FakePath, **kwargs) self.check_unpack_archive_with_converter(format, FakePath, **kwargs) def check_unpack_archive_with_converter(self, format, converter, **kwargs): @@ -2116,6 +2114,71 @@ def test_unpack_archive_zip(self): with self.assertRaises(TypeError): self.check_unpack_archive('zip', filter='data') + def test_unpack_archive_zip_badpaths(self): + srcdir = self.mkdtemp() + zipname = os.path.join(srcdir, 'test.zip') + abspath = os.path.join(srcdir, 'abspath') + with zipfile.ZipFile(zipname, 'w') as zf: + zf.writestr(abspath, 'badfile') + zf.writestr(os.sep + abspath, 'badfile') + zf.writestr('/abspath', 'badfile') + zf.writestr('C:/abspath', 'badfile') + zf.writestr('D:\\abspath', 'badfile') + zf.writestr('E:abspath', 'badfile') + zf.writestr('F:/G:/abspath', 'badfile') + zf.writestr('//server/share/abspath', 'badfile') + zf.writestr('\\\\server2\\share\\abspath', 'badfile') + zf.writestr('../relpath', 'badfile') + zf.writestr(os.pardir + os.sep + 'relpath2', 'badfile') + zf.writestr('good/file', 'goodfile') + zf.writestr('good..file', 'goodfile') + + dstdir = os.path.join(self.mkdtemp(), 'dst') + unpack_archive(zipname, dstdir) + self.assertTrue(os.path.isfile(os.path.join(dstdir, 'good', 'file'))) + self.assertTrue(os.path.isfile(os.path.join(dstdir, 'good..file'))) + self.assertFalse(os.path.exists(abspath)) + self.assertFalse(os.path.exists(os.path.join(dstdir, 'abspath'))) + self.assertFalse(os.path.exists(os.path.join(dstdir, 'G_'))) + self.assertFalse(os.path.exists(os.path.join(dstdir, 'server'))) + if os.name != 'nt': + self.assertTrue(os.path.isfile(os.path.join(dstdir, 'C:', 'abspath'))) + self.assertTrue(os.path.isfile(os.path.join(dstdir, 'D:\\abspath'))) + self.assertTrue(os.path.isfile(os.path.join(dstdir, 'E:abspath'))) + self.assertTrue(os.path.isfile(os.path.join(dstdir, 'F:', 'G:', 'abspath'))) + self.assertTrue(os.path.isfile(os.path.join(dstdir, '\\\\server2\\share\\abspath'))) + if os.pardir == '..': + self.assertFalse(os.path.exists(os.path.join(dstdir, '..', 'relpath'))) + self.assertFalse(os.path.exists(os.path.join(dstdir, 'relpath'))) + else: + self.assertTrue(os.path.isfile(os.path.join(dstdir, '..', 'relpath'))) + self.assertFalse(os.path.exists(os.path.join(dstdir, os.pardir, 'relpath2'))) + self.assertFalse(os.path.exists(os.path.join(dstdir, 'relpath2'))) + + dstdir2 = os.path.join(self.mkdtemp(), 'dst') + os.mkdir(dstdir2) + with os_helper.change_cwd(dstdir2): + unpack_archive(zipname, '') + self.assertTrue(os.path.isfile(os.path.join('good', 'file'))) + self.assertTrue(os.path.isfile('good..file')) + self.assertFalse(os.path.exists(abspath)) + self.assertFalse(os.path.exists('abspath')) + self.assertFalse(os.path.exists('C_')) + self.assertFalse(os.path.exists('server')) + if os.name != 'nt': + self.assertTrue(os.path.isfile(os.path.join('C:', 'abspath'))) + self.assertTrue(os.path.isfile('D:\\abspath')) + self.assertTrue(os.path.isfile('E:abspath')) + self.assertTrue(os.path.isfile(os.path.join('F:', 'G:', 'abspath'))) + self.assertTrue(os.path.isfile('\\\\server2\\share\\abspath')) + if os.pardir == '..': + self.assertFalse(os.path.exists(os.path.join('..', 'relpath'))) + self.assertFalse(os.path.exists('relpath')) + else: + self.assertTrue(os.path.isfile(os.path.join('..', 'relpath'))) + self.assertFalse(os.path.exists(os.path.join(os.pardir, 'relpath2'))) + self.assertFalse(os.path.exists('relpath2')) + def test_unpack_registry(self): formats = get_unpack_formats() diff --git a/Lib/zipfile/__init__.py b/Lib/zipfile/__init__.py index e4bf7e97fbd6617..4ccca3749709f25 100644 --- a/Lib/zipfile/__init__.py +++ b/Lib/zipfile/__init__.py @@ -1309,6 +1309,7 @@ class ZipFile: fp = None # Set here since __del__ checks it _windows_illegal_name_trans_table = None + _ignore_invalid_names = False def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=True, compresslevel=None, *, strict_timestamps=True, metadata_encoding=None): @@ -1793,21 +1794,31 @@ def _extract_member(self, member, targetpath, pwd): # build the destination pathname, replacing # forward slashes to platform specific separators. - arcname = member.filename.replace('/', os.path.sep) - - if os.path.altsep: + arcname = member.filename + if os.path.sep != '/': + arcname = arcname.replace('/', os.path.sep) + if os.path.altsep and os.path.altsep != '/': arcname = arcname.replace(os.path.altsep, os.path.sep) # interpret absolute pathname as relative, remove drive letter or # UNC path, redundant separators, "." and ".." components. - arcname = os.path.splitdrive(arcname)[1] + drive, root, arcname = os.path.splitroot(arcname) + if self._ignore_invalid_names and (drive or root): + return None + if self._ignore_invalid_names and os.path.pardir in arcname.split(os.path.sep): + return None invalid_path_parts = ('', os.path.curdir, os.path.pardir) arcname = os.path.sep.join(x for x in arcname.split(os.path.sep) if x not in invalid_path_parts) if os.path.sep == '\\': # filter illegal characters on Windows - arcname = self._sanitize_windows_name(arcname, os.path.sep) + arcname2 = self._sanitize_windows_name(arcname, os.path.sep) + if self._ignore_invalid_names and arcname2 != arcname: + return None + arcname = arcname2 if not arcname and not member.is_dir(): + if self._ignore_invalid_names: + return None raise ValueError("Empty filename.") targetpath = os.path.join(targetpath, arcname) diff --git a/Misc/NEWS.d/next/Security/2026-03-29-12-51-33.gh-issue-146581.4vZfB0.rst b/Misc/NEWS.d/next/Security/2026-03-29-12-51-33.gh-issue-146581.4vZfB0.rst new file mode 100644 index 000000000000000..98e65549d79016f --- /dev/null +++ b/Misc/NEWS.d/next/Security/2026-03-29-12-51-33.gh-issue-146581.4vZfB0.rst @@ -0,0 +1,5 @@ +Fix vulnerability in :func:`shutil.unpack_archive` for ZIP files on Windows +which allowed to write files outside of the destination tree if the patch in +the archive contains a Windows drive prefix. Now such invalid paths will be +skipped. Files containing ".." in the name (like "foo..bar") are no longer +skipped. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]