# CVE-2025-56005

## Summary

- **CVE ID:** CVE-2025-56005
- **Severity:** UNKNOWN
- **CVSS Score:** 0.88 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Jan 20, 2026
- **Last Modified:** Sep 17, 2026

## Description

An undocumented and unsafe feature in the PLY (Python Lex-Yacc) library 3.11 allows Remote Code Execution (RCE) via the `picklefile` parameter in the `yacc()` function. This parameter accepts a `.pkl` file that is deserialized with `pickle.load()` without validation. Because `pickle` allows execution of embedded code via `__reduce__()`, an attacker can achieve code execution by passing a malicious pickle file. The parameter is not mentioned in official documentation or the GitHub repository, yet it is active in the PyPI version. This introduces a stealthy backdoor and persistence risk. NOTE: A third-party states that this vulnerability should be rejected because the proof of concept does not demonstrate arbitrary code execution and fails to complete successfully.

## Affected Products

- n/a — n/a (n/a)

## References

- [CNA](https://github.com/bohmiiidd/Undocumented-RCE-in-PLY)
- [CNA](https://github.com/tom025/ply_exploit_rejection)
- [CNA](https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005)
- [CNA](https://github.com/tom025/ply_exploit_rejection/issues/1)
- [CVE](http://www.openwall.com/lists/oss-security/2026/01/23/4)
- [CVE](http://www.openwall.com/lists/oss-security/2026/01/23/5)
- [CVE](http://www.openwall.com/lists/oss-security/2026/01/28/5)
- [CVE](http://www.openwall.com/lists/oss-security/2026/01/29/1)
- [CVE](http://www.openwall.com/lists/oss-security/2026/01/29/2)
- [CVE](http://www.openwall.com/lists/oss-security/2026/01/30/1)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2025-56005)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2431308)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-56005.json)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 19.07%
- **EPSS Percentile:** 97.2

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._