CVE-2025-56005

DOCUMENTATION: The CVE program describes this issue as: 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. 

            STATEMENT: This vulnerability rates as Important rather than Critical because it only affects applications using an undocumented parameter (picklefile) in legacy PLY versions 3.2-3.11, which was designed for an atypical use case (Jython environments with oversized parser tables). Exploitation requires the target application to have explicitly implemented this undocumented parameter in their code and depends on the attacker's ability to influence which pickle file gets loaded—whether through shared directory race conditions, configuration injection, supply chain compromise, or chaining with separate vulnerabilities like file upload or path traversal—making this a conditional, context-dependent vulnerability rather than a universally exploitable critical flaw.