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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | ply | No fix yet | — |
| Debian 13 | ply | No fix yet | — |
| Debian 12 | ply | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | ply | No fix yet | — |
| Ubuntu 24.04 LTS | ply | No fix yet | — |
| Ubuntu 22.04 LTS | ply | No fix yet | — |
| Ubuntu 20.04 LTS | ply | No fix yet | — |
| Ubuntu 18.04 LTS | ply | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | ply | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-jsonpath-ng | 1.8.0-1.1 | openSUSE-SU-2026:10418-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | policycoreutils +7 | 3.4-6.amzn2023.0.3 | ALAS2023-2026-1663 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 3 repositories
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gdfurr98/ply-safepickle ★ 0 · Sep 27, 2026
This is a modified version of PLY 3.11, from PyPI (current defunct git repo is not current to PyPI) which reimplements the pickle function in yacc.py to resolve CVE-2025-56005.
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gdfurr98/ply-cve-2025-56005-lab ★ 0 · Sep 27, 2026
Lab demonstrating that CVE-2025-56005 is real and does allow arbitrary code execution at a minimum (the debate about RCE notwithstanding here), and shows that ply-safepickle does block the exploit pa…
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tom025/ply_exploit_rejection ★ 0 · Jan 27, 2026
Arguments to reject CVE-2025-56005
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 3
- WID-SEC-2026-1730 Xerox FreeFlow Print Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · Jul 16, 2026
- ALAS2023-2026-1663 Moderate: policycoreutils security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · May 13, 2026
- openSUSE-SU-2026:10418-1 python311-jsonpath-ng-1.8.0-1.1 on GA media SUSE / openSUSE Security Updates · Mar 25, 2026