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.
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Affected Vendors & Products
Advisories
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Fixes
Solution
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Workaround
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References
| Link | Providers |
|---|---|
| https://github.com/bohmiiidd/Undocumented-RCE-in-PLY |
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History
Tue, 20 Jan 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-502 | |
| Metrics |
cvssV3_1
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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 |
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Status: PUBLISHED
Assigner: mitre
Published:
Updated: 2026-01-20T18:49:29.501Z
Reserved: 2025-08-16T00:00:00.000Z
Link: CVE-2025-56005
No data.
Status : Received
Published: 2026-01-20T19:15:49.247
Modified: 2026-01-20T19:15:49.247
Link: CVE-2025-56005
No data.
OpenCVE Enrichment
No data.
Weaknesses