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Public proof of conceptFix available

CVE-2025-56005

A public proof of concept exists; no exploitation attested.

  • Published2026-01-20
  • WeaknessCWE-502

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-01-2019:15CVE publishedNVD

Versions per branch

NVD
Dabeaz ply
BranchAffectedFixed in
3.11= 3.11no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • plyUbuntu:25.10all versions · no fixed version listed
  • plyUbuntu:24.04:LTSall versions · no fixed version listed
  • plyUbuntu:22.04:LTSall versions · no fixed version listed
  • plyUbuntu:20.04:LTSall versions · no fixed version listed
  • plyUbuntu:18.04:LTSall versions · no fixed version listed
  • plyUbuntu:16.04:LTSall versions · no fixed version listed
  • plyDebian:14all versions · no fixed version listed
  • plyDebian:13all versions · no fixed version listed

8 more package ranges on OSV.dev

Vendor advisories

  • CVE-2025-56005 Red Hat Product Security47 known affected

    ply: python-ply: Unsafe pickle file handling in Ply

    rhmtc/openshift-migration-rhel8-operator as a component of Migration Toolkit for Containers · migration-toolkit-virtualization/mtv-must-gather-rhel8 as a component of Migration Toolkit for Virtualization · migration-toolkit-virtualization/mtv-rhel9-operator as a component of Migration Toolkit for Virtualization · +44 more

Full record on NVD

Fix

  1. Workaround from the vendor Red Hat Product Security CVE-2025-56005 · 47 productsExploitation requires an application to explicitly use PLY's undocumented `picklefile` parameter when calling `ply.yacc.yacc()` and requires an attacker to be able to supply or modify the pickle file that is loaded. Applications can avoid this issue by not using the undocumented `picklefile` parame…
  2. No fix available, says the vendor Red Hat Product Security CVE-2025-56005 · 29 productsAffected
  3. No fix planned, says the vendor Red Hat Product Security CVE-2025-56005 · 18 productsWill not fix

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2026-01-20
Last Modified
2026-09-17
NVD status
Modified
GitHub Advisory
GHSA-qc6m-pwr3-g72p

Frequently asked questions

What is CVE-2025-56005?

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.

Is CVE-2025-56005 actively exploited?

A proof-of-concept exploit exists for CVE-2025-56005, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2025-56005?

CVE-2025-56005 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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Sources for this record