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CVE-2025-56005

9.8 · CRITICAL

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.

Published Jan 20, 2026CWE-502EPSS 18.81%

Overview

CVE-2025-56005 is a critical-severity vulnerability. It was published on January 20, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/bohmiiidd/Undocumented-RCE-in-PLYGitHubgithub.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005GitHubgithub.com/tom025/ply_exploit_rejectionGitHubgithub.com/tom025/ply_exploit_rejection/issues/1Refwww.openwall.com/lists/oss-security/2026/01/23/4Refwww.openwall.com/lists/oss-security/2026/01/23/5Refwww.openwall.com/lists/oss-security/2026/01/28/5Refwww.openwall.com/lists/oss-security/2026/01/29/1Refwww.openwall.com/lists/oss-security/2026/01/29/2Refwww.openwall.com/lists/oss-security/2026/01/30/1

How CyberStrike helps

Frequently asked questions

What is CVE-2025-56005?

CVE-2025-56005 is a critical-severity vulnerability. It was published on January 20, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2025-56005?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2025-56005?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-56005?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-56005 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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