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.
CVSS Details
- CVSS 3.1 Base Score: 9.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade policycoreutils-debugsourceUpgrade policycoreutils-devel-debuginfoUpgrade policycoreutils-guiUpgrade policycoreutils-python-utilsUpgrade policycoreutils-dbusUpgrade policycoreutils-restorecondUpgrade policycoreutils-restorecond-debuginfoUpgrade policycoreutils-newroleUpgrade policycoreutilsUpgrade policycoreutils-debuginfoUpgrade python3-policycoreutilsUpgrade policycoreutils-develUpgrade policycoreutils-newrole-debuginfo | May 19, 2026 | Jan 20, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Jan 20, 2026 |
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