Description (CNA)
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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| n/a / n/a | affected n/a |
CWE
No CWE identifiers supplied.
References
- https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
- https://github.com/tom025/ply_exploit_rejection
- https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
- https://github.com/tom025/ply_exploit_rejection/issues/1
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.
- 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
An arbitrary code execution vulnerability was discovered in PLY (Python Lex-Yacc). When an application uses PLY's undocumented picklefile parameter to load cached parser data, the library deserializes the pickle file without validation. If an attacker can supply or modify the pickle file being loaded, they can embed malicious code that executes automatically during the deserialization process, potentially allowing them to run arbitrary commands on the affected system.