# CVE-2025-71343: picklescan detection bypass via lib2to3 ParserGenerator

Source: https://junglewise.ai/threats/cve-2025-71343-picklescan-detection-bypass-via-lib2to3-parsergenerator  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-04. Updated: 2026-07-04  
License: CC BY 4.0 with a link back

CVE-2025-71343 · Severity: high · CVSS 8.1 · Published 2026-07-04

picklescan is a security tool used to scan Python pickle files and machine learning models (like PyTorch) for malicious code. A vulnerability was discovered where the tool fails to detect certain types of hidden commands embedded within these files. If a user relies on this tool to verify a file and then opens it, an attacker could execute arbitrary commands on the user's system, potentially leading to a full system compromise or data theft.

Technologies: [picklescan (PyPI)](https://junglewise.ai/threats/technologies/picklescan). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2025-71343 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-71343 being exploited in the wild.

**How severe is CVE-2025-71343?** High severity, with a CVSS score of 8.1, published 4 July 2026.

**Which products and versions are affected?** picklescan (PyPI) ECOSYSTEM:introduced=0,fixed=0.0.30.

**Is there a fix for CVE-2025-71343?** Yes. picklescan (PyPI): upgrade to 0.0.30 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-71343 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2025-71343?** Check whether you run picklescan (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- picklescan (PyPI): upgrade to 0.0.30 or later

  ```sh
  pip install "picklescan>=0.0.30"
  ```


## Technical details

A deserialization bypass vulnerability exists in picklescan versions prior to 0.0.30. The scanner fails to identify malicious payloads that utilize the 'lib2to3.pgen2.pgen.ParserGenerator.make_label' function within a pickle's __reduce__ method. An attacker can craft a malicious pickle file that evades detection by picklescan but executes arbitrary Python code when processed by pickle.load(). This is achieved by embedding system commands within the label argument of the make_label function. The vulnerability is addressed in version 0.0.30.

## Affected products

- picklescan picklescan < 0.0.30

## Identifiers

- CVE-2025-71343
- GHSA-p9w7-82w4-7q8m

## Timeline

- 2025-08-26: advisory: GitHub Security Advisory published
- 2026-07-04: disclosed: NVD publication date
- 2025-08-26: patched: Version 0.0.30 released to address the bypass

## References

- [https://github.com/mmaitre314/picklescan/security/advisories/GHSA-p9w7-82w4-7q8m](https://github.com/mmaitre314/picklescan/security/advisories/GHSA-p9w7-82w4-7q8m)
- [https://www.vulncheck.com/advisories/picklescan-arbitrary-code-execution-via-lib2to3-pgen2-pgen-parsergenerator-make-label-detection-bypass](https://www.vulncheck.com/advisories/picklescan-arbitrary-code-execution-via-lib2to3-pgen2-pgen-parsergenerator-make-label-detection-bypass)

## Related threats

- [picklescan detection bypass via _operator.methodcaller](https://junglewise.ai/threats/cve-2025-71375-picklescan-detection-bypass-via-operator-methodcaller)
- [picklescan security bypass via operator.methodcaller](https://junglewise.ai/threats/cve-2025-71373-picklescan-security-bypass-via-operator-methodcaller)
- [Picklescan detection bypass via numpy getlincoef gadget](https://junglewise.ai/threats/cve-2025-71372-picklescan-detection-bypass-via-numpy-getlincoef-gadget)
- [picklescan safety check bypass via PyTorch decoder basichandlers](https://junglewise.ai/threats/cve-2025-71369-picklescan-safety-check-bypass-via-pytorch-decoder-basichandlers)
- [picklescan security bypass via _operator.attrgetter function call](https://junglewise.ai/threats/cve-2025-71367-picklescan-security-bypass-via-operator-attrgetter-function-call)