CVE-2025-56005
PLY Python Lex-Yacc Remote Code Execution (RCE) via Unvalidated Pickle File
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.
INFO
Published Date :
Jan. 20, 2026, 7:15 p.m.
Last Modified :
Feb. 6, 2026, 8:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update the PLY library to the latest secure version.
- Remove or disable the picklefile parameter if possible.
- Avoid deserializing untrusted pickle files.
Public PoC/Exploit Available at Github
CVE-2025-56005 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-56005.
| URL | Resource |
|---|---|
| https://github.com/bohmiiidd/Undocumented-RCE-in-PLY | Exploit 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 | Exploit Mitigation 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 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-56005 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-56005
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Clarification Regarding the Rejection Arguments
Arguments to reject CVE-2025-56005
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-56005 vulnerability anywhere in the article.
-
CybersecurityNews
Critical Vulnerability in Python PLY Library Enables Remote Code Execution – PoC Published
A critical vulnerability has been identified in the PyPI-distributed version of PLY (Python Lex-Yacc) 3.11, allowing arbitrary code execution through unsafe deserialization of untrusted pickle files. ... Read more
The following table lists the changes that have been made to the
CVE-2025-56005 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Feb. 06, 2026
Action Type Old Value New Value Added Tag disputed Changed 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. 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. Added Reference https://github.com/tom025/ply_exploit_rejection/issues/1 -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jan. 30, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/01/30/1 -
Initial Analysis by [email protected]
Jan. 30, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:dabeaz:ply:3.11:*:*:*:*:*:*:* Added Reference Type MITRE: https://github.com/bohmiiidd/Undocumented-RCE-in-PLY Types: Exploit, Third Party Advisory Added Reference Type MITRE: https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005 Types: Exploit, Third Party Advisory Added Reference Type MITRE: https://github.com/tom025/ply_exploit_rejection Types: Exploit, Mitigation, Third Party Advisory Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/01/23/4 Types: Exploit, Mailing List Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/01/23/5 Types: Mailing List Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/01/28/5 Types: Exploit, Mailing List Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/01/29/1 Types: Exploit, Mailing List Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/01/29/2 Types: Mailing List -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jan. 29, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/01/29/2 -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jan. 29, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/01/29/1 -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jan. 29, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/01/28/5 -
CVE Modified by [email protected]
Jan. 28, 2026
Action Type Old Value New Value Added Reference https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005 -
CVE Modified by [email protected]
Jan. 28, 2026
Action Type Old Value New Value Added Reference https://github.com/tom025/ply_exploit_rejection -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jan. 23, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/01/23/5 -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jan. 23, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/01/23/4 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jan. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-502 -
New CVE Received by [email protected]
Jan. 20, 2026
Action Type Old Value New Value Added 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. Added Reference https://github.com/bohmiiidd/Undocumented-RCE-in-PLY