CVE-2025-56005

Summary

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 Software

Weaknesses

• n/a

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: yes
  • Technical Impact: total

CVE Program Container

Additional References

• 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

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

Additional References

• 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

References

• https://github.com/bohmiiidd/Undocumented-RCE-in-PLY
• https://github.com/tom025/ply_exploit_rejection
• https://github.com/bohmiiidd/Undocumument_RCE_PLY-yacc-CVE-2025-56005
• https://github.com/tom025/ply_exploit_rejection/issues/1

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