Remote Code Execution Vulnerability in PLY Library by Python
CVE-2025-56005

9.8CRITICAL

Key Information:

Vendor

Python

Status
PLY (Python Lex-Yacc)
Vendor
CVE Published:
20 January 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2025-56005?

An undocumented and unsafe feature in the PLY library version 3.11 presents a significant security risk, allowing remote code execution via the picklefile parameter in the yacc() function. This parameter accepts .pkl files, which are deserialized using pickle.load() without any form of validation. Since pickle permits the execution of embedded code through the __reduce__() method, an attacker can exploit this by providing a malicious pickle file, leading to unauthorized code execution and creating potential stealthy backdoors. Remarkably, this parameter is not documented in the official resources and remains active in the PyPI version, amplifying the persistence risk for systems relying on this library.

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Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

ply_exploit_rejection
Created by tom025

Undocumument_RCE_PLY-yacc-CVE-2025-56005
Created by bohmiiidd

References

https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
https://github.com/tom025/ply_exploit_rejection
https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CV...

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

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