PYSEC-2026-1783

Vulnerability from pysec - Published: 2026-07-07 16:03 - Updated: 2026-07-07 17:25
VLAI
Details

Summary

Picklescan uses the numpy.f2py.crackfortran._eval_length function (a NumPy F2PY helper) to execute arbitrary Python code during unpickling.

Details

Picklescan fails to detect a malicious pickle that uses the gadget numpy.f2py.crackfortran._eval_length in __reduce__, allowing arbitrary command execution when the pickle is loaded. A crafted object returns this function plus attacker‑controlled arguments; the scan reports the file as safe, but pickle.load() triggers execution.

PoC

class PoC:
    def __reduce__(self):
        from numpy.f2py.crackfortran import _eval_length
        return _eval_length, ("__import__('os').system('whoami')", None)

Impact

  • Arbitrary code execution on the victim machine once they load the “scanned as safe” pickle / model file.
  • Affects any workflow relying on Picklescan to vet untrusted pickle / PyTorch artifacts.
  • Enables supply‑chain poisoning of shared model files.

Credits

Severity
6.7 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P
Impacted products
Name purl
picklescan pkg:pypi/picklescan
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "picklescan",
        "purl": "pkg:pypi/picklescan"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.33"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.0.1",
        "0.0.10",
        "0.0.11",
        "0.0.12",
        "0.0.13",
        "0.0.14",
        "0.0.15",
        "0.0.16",
        "0.0.17",
        "0.0.18",
        "0.0.19",
        "0.0.2",
        "0.0.20",
        "0.0.21",
        "0.0.22",
        "0.0.23",
        "0.0.24",
        "0.0.25",
        "0.0.26",
        "0.0.27",
        "0.0.28",
        "0.0.29",
        "0.0.3",
        "0.0.30",
        "0.0.31",
        "0.0.32",
        "0.0.4",
        "0.0.5",
        "0.0.6",
        "0.0.7",
        "0.0.8",
        "0.0.9"
      ]
    }
  ],
  "aliases": [
    "CVE-2025-71339",
    "GHSA-6556-fwc2-fg2p"
  ],
  "details": "### Summary\n\nPicklescan uses the `numpy.f2py.crackfortran._eval_length` function (a NumPy F2PY helper) to execute arbitrary Python code during unpickling.\n\n### Details\n\nPicklescan fails to detect a malicious pickle that uses the gadget `numpy.f2py.crackfortran._eval_length` in `__reduce__`, allowing arbitrary command execution when the pickle is loaded. A crafted object returns this function plus attacker\u2011controlled arguments; the scan reports the file as safe, but pickle.load() triggers execution.\n\n### PoC\n```python\nclass PoC:\n    def __reduce__(self):\n        from numpy.f2py.crackfortran import _eval_length\n        return _eval_length, (\"__import__(\u0027os\u0027).system(\u0027whoami\u0027)\", None)\n```\n\n### Impact\n\n- Arbitrary code execution on the victim machine once they load the \u201cscanned as safe\u201d pickle / model file.\n- Affects any workflow relying on Picklescan to vet untrusted pickle / PyTorch artifacts.\n- Enables supply\u2011chain poisoning of shared model files.\n\n### Credits\n- [ac0d3r](https://github.com/ac0d3r)\n- [Tong Liu](https://lyutoon.github.io), Institute of information engineering, CAS",
  "id": "PYSEC-2026-1783",
  "modified": "2026-07-07T17:25:02.114122Z",
  "published": "2026-07-07T16:03:14.498992Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/security/advisories/GHSA-6556-fwc2-fg2p"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/pull/53"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/commit/70c1c6c31beb6baaf52c8db1b6c3c0e84a6f9dab"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mmaitre314/picklescan"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/releases/tag/v0.0.33"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/picklescan"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-6556-fwc2-fg2p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71339"
    }
  ],
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Picklescan is vulnerable to RCE through missing detection when calling numpy.f2py.crackfortran._eval_length"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.