CVE-2025-56005CRITICAL 9.8EPSS p96.9%
CVE-2025-56005CVE-2025-56005
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.
Scoring
| CVSS 3.1 | 9.8 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 18.65% probability of exploitation · percentile 96.9% · 2026-06-19T12:03:05Z |
| Published | 2026-01-20 |
| Last modified | 2026-02-06 |
Underlying weaknesses· 1
References
- https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
- https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
- https://github.com/tom025/ply_exploit_rejection
- https://github.com/tom025/ply_exploit_rejection/issues/1
- http://www.openwall.com/lists/oss-security/2026/01/23/4
- http://www.openwall.com/lists/oss-security/2026/01/23/5
- http://www.openwall.com/lists/oss-security/2026/01/28/5
- http://www.openwall.com/lists/oss-security/2026/01/29/1
1
| Type | Target | Confidence | Tier |
|---|---|---|---|
| Weakness | Deserialization of Untrusted Datacwe-502 | 0% | live |
Related by meaning· 6
Nearest entities by semantic similarity across the cs-graph corpus.