CVE-2025-56005

9.8 CRITICAL
Published: January 20, 2026 Modified: February 06, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
Source: cve@mitre.org
Exploit Third Party Advisory
https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
Source: cve@mitre.org
Exploit Third Party Advisory
https://github.com/tom025/ply_exploit_rejection
Source: cve@mitre.org
Exploit Mitigation Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/01/23/4
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Mailing List
http://www.openwall.com/lists/oss-security/2026/01/23/5
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List
http://www.openwall.com/lists/oss-security/2026/01/28/5
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Mailing List
http://www.openwall.com/lists/oss-security/2026/01/29/1
Source: af854a3a-2127-422b-91ae-364da2661108
Exploit Mailing List
http://www.openwall.com/lists/oss-security/2026/01/29/2
Source: af854a3a-2127-422b-91ae-364da2661108
Mailing List
http://www.openwall.com/lists/oss-security/2026/01/30/1
Source: af854a3a-2127-422b-91ae-364da2661108

10 reference(s) from NVD

Quick Stats

CVSS v3 Score
9.8 / 10.0
EPSS (Exploit Probability)
0.9%
76th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

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