# CVE-2025-71339: Picklescan - Arbitrary Code Execution via numpy.f2py.crackfortran._eval_length Gadget

> Attackers can bypass Picklescan's safety checks to execute arbitrary code via malicious pickle files using a specific numpy gadget.

- **Severity:** High 7.6 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** GHSA-6556-fwc2-fg2p, PYSEC-2026-1783

## What is CVE-2025-71339?

CVE-2025-71339 is a high-severity unsafe deserialization vulnerability in Picklescan, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Picklescan before 0.0.33 fails to detect the numpy.f2py.crackfortran._eval_length gadget in pickle __reduce__ methods, allowing arbitrary code execution. Attackers can craft malicious pickle files that execute arbitrary Python code when loaded by victims who trust Picklescan's safety validation.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2025-71339?

3 open source packages ship an affected version, including picklescan.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `picklescan` | PyPI | All versions | 0.0.33 |
| `picklescan` | PyPI | All versions | 0.0.33 |
| `picklescan` | PyPI | All versions | 0.0.33 |

## How do I fix CVE-2025-71339?

Upgrade picklescan to 0.0.33 or later.

## Is CVE-2025-71339 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-71339 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-71339 and fix it if it is affected.

What it is: CVE-2025-71339 is a high-severity unsafe deserialization vulnerability in Picklescan, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-71339 exists.

Affected packages and fixed versions:
- picklescan (PyPI): affected all versions; fixed in 0.0.33
- picklescan (PyPI): affected all versions; fixed in 0.0.33
- picklescan (PyPI): affected all versions; fixed in 0.0.33

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-71339/ (Markdown: https://insights.sbomify.com/CVE-2025-71339/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71339
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71339
- OSV: https://osv.dev/vulnerability/CVE-2025-71339

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71339/
Summaries are generated and may contain mistakes; the official description above is the record.