Critical 9.8Published Jan 19, 2026

CVE-2025-56005An 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.

Updated under an hour ago (Oct 27, 2026, 4:30 AM ET)

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It affects Red Hat Fence Agents Remediation Operator and 19 other products. Add what you run to find out whether that includes you.

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Exploited in the last 30 days

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: 9.8 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-502
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: mitre
NVD analysis: Modified
Record last updated: Sep 17, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Red Hat Fence Agents Remediation Operator redhat:workload_availability_far	0	CISA ADP
Red Hat Migration Toolkit for Containers redhat:rhmt	1	CISA ADP
Red Hat Migration Toolkit for Virtualization redhat:migration_toolkit_virtualization	2	CISA ADP
Red Hat OpenShift Developer Tools and Services redhat:ocp_tools	All versions	CISA ADP
Red Hat OpenShift Pipelines redhat:openshift_pipelines	1	CISA ADP
Red Hat OpenShift Service Mesh 2 redhat:service_mesh	2	CISA ADP
Red Hat Red Hat Advanced Cluster Security 4 redhat:advanced_cluster_security	4	CISA ADP
Red Hat Red Hat Ansible Automation Platform Ansible Core 2 redhat:ansible_core	2	CISA ADP
Red Hat Red Hat Ceph Storage 7 redhat:ceph_storage	7	CISA ADP
Red Hat Red Hat Certification Program for Red Hat Enterprise Linux 9 redhat:certifications	9	CISA ADP
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References

References

https://github.com/bohmiiidd/Undocumented-RCE-in-PLY	exploit, third-party-advisory
https://github.com/tom025/ply_exploit_rejection	exploit, mitigation, third-party-advisory
https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005	exploit, third-party-advisory
https://github.com/tom025/ply_exploit_rejection/issues/1
http://www.openwall.com/lists/oss-security/2026/01/23/4	exploit, mailing-list
http://www.openwall.com/lists/oss-security/2026/01/23/5	mailing-list
http://www.openwall.com/lists/oss-security/2026/01/28/5	exploit, mailing-list
http://www.openwall.com/lists/oss-security/2026/01/29/1	exploit, mailing-list
http://www.openwall.com/lists/oss-security/2026/01/29/2	mailing-list
http://www.openwall.com/lists/oss-security/2026/01/30/1
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.