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 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 Jan 21, 2026

https://github.com/bohmiiidd/Undocumented-RCE-in-PLY

CVSS ScoreCritical

9.8

Ecosystem	Package	Version

Ecosystem	Package	Version

Vulnerabilities

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 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 Jan 21, 2026

https://github.com/bohmiiidd/Undocumented-RCE-in-PLY

CVSS ScoreCritical

9.8


npm	flamassembly	1.3.0
pypi	ply	3.11
rpm	python-ply	3.11-10.module+el8.4.0+20068+32a535e2
rpm	python-ply	3.11-10.module+el8.4.0+20109+b7b1db01
rpm	python-ply	3.11-10.module+el8.9.0+90016+9c2d6573
rpm	python-ply	3.11-10.module+el8.9.0+90017+9913aa0c
rpm	python-ply	3.11-14.0.1.el9
rpm	python-ply	3.11-14.el9
rpm	python-ply	3.11-24.el10
rpm	python-ply	3.11-25.el10
rpm	python-ply	3.11-8.module+el8.2.0+5579+085cd3bd
rpm	python-ply	3.11-8.module+el8.3.0+7824+e0098946
rpm	python3.11-ply	3.11-1.el8
rpm	python3.11-ply	3.11-1.el9
rpm	python3.12-ply	3.11-2.el8
rpm	python3.12-ply	3.11-2.el9
rpm	rh-python38-python-ply	3.11-9.el7

Ecosystem	Package	Version


npm	flamassembly	1.3.0
pypi	ply	3.11
rpm	python-ply	3.11-10.module+el8.4.0+20068+32a535e2
rpm	python-ply	3.11-10.module+el8.4.0+20109+b7b1db01
rpm	python-ply	3.11-10.module+el8.9.0+90016+9c2d6573
rpm	python-ply	3.11-10.module+el8.9.0+90017+9913aa0c
rpm	python-ply	3.11-14.0.1.el9
rpm	python-ply	3.11-14.el9
rpm	python-ply	3.11-24.el10
rpm	python-ply	3.11-25.el10
rpm	python-ply	3.11-8.module+el8.2.0+5579+085cd3bd
rpm	python-ply	3.11-8.module+el8.3.0+7824+e0098946
rpm	python3.11-ply	3.11-1.el8
rpm	python3.11-ply	3.11-1.el9
rpm	python3.12-ply	3.11-2.el8
rpm	python3.12-ply	3.11-2.el9
rpm	rh-python38-python-ply	3.11-9.el7

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CVE-2025-56005

CVE-2025-56005