anonhaven

CVE-2025-56005

CRITICAL CVSS 3.1: 9.8 EPSS 16.9%
Updated Aug 07, 2026
Dabeaz
Parameter Value
CVSS 9.8 (CRITICAL)
Type CWE-502 (Deserialization of Untrusted Data)
Vendor Dabeaz
Public PoC Yes

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)

CWE-502 Deserialization of Untrusted Data

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Dabeaz Ply
cpe:2.3:a:dabeaz:ply:3.11:*:*:*:*:*:*:*
 — —

References 13

https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
cve@mitre.org
https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
cve@mitre.org
https://github.com/tom025/ply_exploit_rejection
cve@mitre.org
https://github.com/tom025/ply_exploit_rejection/issues/1
cve@mitre.org
http://www.openwall.com/lists/oss-security/2026/01/23/4
af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/01/23/5
af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/01/28/5
af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/01/29/1
af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/01/29/2
af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/01/30/1
af854a3a-2127-422b-91ae-364da2661108
https://access.redhat.com/security/cve/CVE-2025-56005
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://bugzilla.redhat.com/show_bug.cgi?id=2431308
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-56005.json
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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