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CRITICAL

CVE-2025-56005

CVSS v3

9.8

CRITICAL

EPSS Score

19.1 %

exploit probability, as of 2026-09-25

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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

Technical details

Published
2026-01-20
Last Modified
2026-02-06

Frequently asked questions

What is CVE-2025-56005?

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

Is CVE-2025-56005 actively exploited?

Active exploitation of CVE-2025-56005 has not been confirmed. Its EPSS score was 19.1% on 2026-09-25, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2025-56005?

CVE-2025-56005 has a CVSS v3 base score of 9.8 (CRITICAL severity).

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