CVE-2025-56005
Dabeaz Ply remote code execution
- Published20 Jan 2026
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. 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 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.
References
- https://access.redhat.com/security/cve/CVE-2025-56005
- https://bugzilla.redhat.com/show_bug.cgi?id=2431308
- https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
- https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
- https://github.com/tom025/ply_exploit_rejection
- https://github.com/tom025/ply_exploit_rejection/issues/1
- https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-56005.json
- 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
and 3 more references
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2025-56005 being actively exploited?
CVE-2025-56005 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 19.1%.
How severe is CVE-2025-56005?
CVE-2025-56005 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 19.1% probability of exploitation.
Which products are affected by CVE-2025-56005?
Affected products include Dabeaz Ply.
How do I fix CVE-2025-56005?
Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2025-56005 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.