CVE-2025-56005 - Vulnerability Details

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.

Published: 2026-01-20

Score: 9.8 Critical

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

n/a

affected

Version	Status	Constraints
`n/a`	affected	—

Configuration 1 [-]

cpe:2.3:a:dabeaz:ply:3.11:*:*:*:*:*:*:*

No data.

Vendor	Product	Confidence	Versions
Python	Ply	—	—

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Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00816.

Exploitation poc

Automatable yes

Technical Impact total

References

Link	Providers
http://www.openwall.com/lists/oss-security/2026/01/23/4
http://www.openwall.com/lists/oss-security/2026/01/23/5
http://www.openwall.com/lists/oss-security/2026/01/28/5
http://www.openwall.com/lists/oss-security/2026/01/29/1
http://www.openwall.com/lists/oss-security/2026/01/29/2
http://www.openwall.com/lists/oss-security/2026/01/30/1
https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
https://github.com/tom025/ply_exploit_rejection
https://github.com/tom025/ply_exploit_rejection/issues/1
https://nvd.nist.gov/vuln/detail/CVE-2025-56005
https://www.cve.org/CVERecord?id=CVE-2025-56005

History

Fri, 06 Feb 2026 20:00:00 +0000

Type	Values Removed	Values Added
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.	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.
References		https://github.com/tom025/ply_exploit_rejection/issues/1

Fri, 30 Jan 2026 23:30:00 +0000

Type	Values Removed	Values Added
References		http://www.openwall.com/lists/oss-security/2026/01/30/1

Fri, 30 Jan 2026 20:15:00 +0000

Type	Values Removed	Values Added
First Time appeared		Dabeaz Dabeaz ply
CPEs		cpe:2.3:a:dabeaz:ply:3.11:::::::*
Vendors & Products		Dabeaz Dabeaz ply

Thu, 29 Jan 2026 20:30:00 +0000

Type	Values Removed	Values Added
References		http://www.openwall.com/lists/oss-security/2026/01/29/2

Thu, 29 Jan 2026 19:30:00 +0000

Type	Values Removed	Values Added
References		http://www.openwall.com/lists/oss-security/2026/01/29/1

Thu, 29 Jan 2026 00:30:00 +0000

Type	Values Removed	Values Added
References		http://www.openwall.com/lists/oss-security/2026/01/28/5

Wed, 28 Jan 2026 20:30:00 +0000

Type	Values Removed	Values Added
References		https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005

Wed, 28 Jan 2026 06:30:00 +0000

Type	Values Removed	Values Added
References		https://github.com/tom025/ply_exploit_rejection

Fri, 23 Jan 2026 22:30:00 +0000

Type	Values Removed	Values Added
References		http://www.openwall.com/lists/oss-security/2026/01/23/5

Fri, 23 Jan 2026 21:30:00 +0000

Type	Values Removed	Values Added
References		http://www.openwall.com/lists/oss-security/2026/01/23/4

Thu, 22 Jan 2026 12:15:00 +0000

Type	Values Removed	Values Added
Title		ply: From CVEorg collector
References		https://nvd.nist.gov/vuln/detail/CVE-2025-56005 https://www.cve.org/CVERecord?id=CVE-2025-56005
Metrics	threat_severity `None`	threat_severity `Critical`

Wed, 21 Jan 2026 11:30:00 +0000

Type	Values Removed	Values Added
First Time appeared		Python Python ply
Vendors & Products		Python Python ply

Tue, 20 Jan 2026 20:15:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Tue, 20 Jan 2026 19:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-502
Metrics		cvssV3_1 `{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}`

Tue, 20 Jan 2026 18:30:00 +0000

Type	Values Removed	Values Added
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.
References		https://github.com/bohmiiidd/Undocumented-RCE-in-PLY

Subscriptions

Dabeaz Ply

Python Ply

MITRE

Status: PUBLISHED

Assigner: mitre

Published: 2026-01-20T00:00:00.000Z

Updated: 2026-02-06T19:55:53.916Z

Reserved: 2025-08-16T00:00:00.000Z

Link: CVE-2025-56005

Vulnrichment

Updated: 2026-01-30T23:06:25.298Z

NVD

Status : Modified

Published: 2026-01-20T19:15:49.247

Modified: 2026-02-06T20:16:08.237

Link: CVE-2025-56005

Redhat

Severity : Critical

Publid Date: 2026-01-20T00:00:00Z

Links: CVE-2025-56005 - Bugzilla

OpenCVE Enrichment

Updated: 2026-01-21T11:20:02Z

Weaknesses

CWE-502

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Exploitation poc

Automatable yes

Technical Impact total

Subscriptions

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