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.
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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, NVD)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
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
dabeaz ply dabeaz:ply | 3.11 | NVD |
References
- https://github.com/bohmiiidd/Undocumented-RCE-in-PLYexploit, third-party-advisory
- https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005exploit, third-party-advisory
- https://github.com/tom025/ply_exploit_rejectionexploit, mitigation, third-party-advisory
- https://github.com/tom025/ply_exploit_rejection/issues/1
- http://www.openwall.com/lists/oss-security/2026/01/23/4exploit, mailing-list
- http://www.openwall.com/lists/oss-security/2026/01/23/5mailing-list
- http://www.openwall.com/lists/oss-security/2026/01/28/5exploit, mailing-list
- http://www.openwall.com/lists/oss-security/2026/01/29/1exploit, mailing-list
- http://www.openwall.com/lists/oss-security/2026/01/29/2mailing-list
- http://www.openwall.com/lists/oss-security/2026/01/30/1
- https://access.redhat.com/security/cve/CVE-2025-56005
- https://bugzilla.redhat.com/show_bug.cgi?id=2431308
- https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-56005.json
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.