CVE-2025-56005

CRITICAL 9.8

CVSS Score

9.8

EPSS Score

0.0%

EPSS Percentile

0th

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.

Vendor	n/a
Product	n/a
Published	Jan 20, 2026
Last Updated	Jun 30, 2026

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Affected Versions

n/a / n/a

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References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/bohmiiidd/Undocumented-RCE-in-PLY github.com: https://github.com/tom025/ply_exploit_rejection github.com: https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005 github.com: https://github.com/tom025/ply_exploit_rejection/issues/1 openwall.com: http://www.openwall.com/lists/oss-security/2026/01/23/4 openwall.com: http://www.openwall.com/lists/oss-security/2026/01/23/5 openwall.com: http://www.openwall.com/lists/oss-security/2026/01/28/5 openwall.com: http://www.openwall.com/lists/oss-security/2026/01/29/1 openwall.com: http://www.openwall.com/lists/oss-security/2026/01/29/2 openwall.com: http://www.openwall.com/lists/oss-security/2026/01/30/1 access.redhat.com: https://access.redhat.com/security/cve/CVE-2025-56005 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2431308 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-56005.json