What’s Vulnerable › Vulnerabilities

CVE-2025-56005

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 18.8% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-01-20 · updated 2026-09-17
• Weakness: CWE-502

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.

Affected products

• Dabeaz Ply: 3.11

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
• http://www.openwall.com/lists/oss-security/2026/01/29/2
• 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

Get alerted when CVE-2025-56005 or the next vulnerability affects your stack