GHSA-73h3-mf4w-8647 Poetry has Path Traversal in tar extraction on Python 3.10.0 - 3.10.12 and 3.11.0 - 3.11.4

• PyPI poetry: < 2.3.4 → fixed in 2.3.4

Summary The `extractall()` function in `src/poetry/utils/helpers.py:410-426` extracts sdist tarballs without path traversal protection on Python versions where `tarfile.data_filter` is unavailable. Considering only Python versions which are still supported by Poetry, these are 3.10.0 - 3.10.12 and 3.11.0 - 3.11.4. Impact Arbitrary file write (path traversal) from untrusted sdist content. In practice, the impact is low because an attacker who exploits this vulnerability can as well include arbitrary code in a `setup.py`, which will be executed when the sdist is built after tar extraction. In other words, a malicious sdist can write arbitrary files by design. However, since it is unexpected and not by design that the file write already happens during tar extraction, this is still considered a vulnerability. On Python 3.11.2 (Debian Bookworm default, directly tested), a crafted sdist with `../../` tar member paths writes files outside the intended extraction directory. The traversal occurs during metadata resolution (`poetry add --lock`), before the build backend is run. Affected Environments: • Python 3.10.0 through 3.10.12 (inclusive): `tarfile.data_filter` absent or broken • Python 3.11.0 through 3.11.4 (inclusive): `tarfile.data_filter` absent or broken • Debian Bookworm: Python 3.11.2 (default) • Ubuntu 22.04 LTS: Python 3.10.6 (default) Patches Versions 2.3.4 and newer of Poetry ensure that paths are inside the target directory. Root Cause File: `src/poetry/utils/helpers.py`, lines 410-426: ```python def extractall(source: Path, dest: Path, zip: bool) -> None: """Extract all members from either a zip or tar archive.""" if zip: with zipfile.ZipFile(source) as archive: archive.extractall(dest) else: broken_tarfile_filter = {(3, 9, 17), (3, 10, 12), (3, 11, 4)} with tarfile.open(source) as archive: if ( hasattr(tarfile, "data_filter") and sys.version_info[:3] not in broken_tarfile_filter ): archive.extractall(dest, filter="data") else: archive.extractall(dest) # None: """Extract all members from either a zip or tar archive.""" if zip: with zipfile.ZipFile(source) as archive: archive.extractall(dest) else: broken_tarfile_filter = {(3, 9, 17), (3, 10, 12), (3, 11, 4)} with tarfile.open(source) as archive: if ( hasattr(tarfile, "data_filter") and sys.version_info[:3] not in broken_tarfile_filter ): archive.extractall(dest, filter="data") else: # Validate all member paths before extraction dest_resolved = dest.resolve() safe_members = [] for member in archive.getmembers(): member_path = (dest_resolved / member.name).resolve() if not member_path.is_relative_to(dest_resolved): raise ValueError( f"Refusing to extract {member.name}: " f"would write outside {dest}" ) if member.issym(): link_target = (member_path.parent / member.linkname).resolve() if not link_target.is_relative_to(dest_resolved): raise ValueError( f"Refusing symlink {member.name}: " f"target {member.linkname} outside {dest}" ) elif member.islnk(): link_target = (dest_resolved / member.linkname).resolve() if not link_target.is_relative_to(dest_resolved): raise ValueError( f"Refusing hardlink {member.name}: " f"target {member.linkname} outside {dest}" ) safe_members.append(member) archive.extractall(dest, members=safe_members) ```