CVE-2025-64512 is a deserialization vulnerability classified under CWE-502 affecting pdfminer.six, a widely used Python library for extracting information from PDF documents. The vulnerability exists in the CMapDB._load_data() function, which uses Python's pickle.loads() to deserialize data from pickle files. Normally, these pickle files are trusted components distributed with pdfminer.six and stored in the cmap/ directory. However, a malicious PDF can specify an alternative directory and filename ending with .pickle.gz, allowing an attacker to supply a malicious, compressed pickle file. When pdfminer.six processes such a PDF, it decompresses and deserializes the pickle file, triggering arbitrary code execution. This can lead to full system compromise, including unauthorized data access, modification, or denial of service. The vulnerability requires user interaction (opening a malicious PDF) and local access (AV:L), but no privileges or authentication are needed. The issue was fixed in version 20251107 by presumably removing or securing the unsafe deserialization mechanism. Although no exploits are reported in the wild, the vulnerability's nature and high CVSS score (8.6) highlight its criticality, especially in environments processing untrusted PDFs automatically or manually.

For European organizations, the impact of CVE-2025-64512 can be significant. Organizations relying on pdfminer.six for automated PDF processing, document indexing, or data extraction in sectors such as finance, government, legal, and healthcare could face severe risks. Exploitation could lead to arbitrary code execution on systems processing malicious PDFs, resulting in data breaches, ransomware deployment, or disruption of critical services. Confidentiality is at risk due to potential data exfiltration, integrity can be compromised by unauthorized modifications, and availability may be affected by denial-of-service conditions or malware payloads. Given the widespread use of pdfminer.six in open-source and commercial tools, the attack surface includes both endpoint and server environments. The requirement for user interaction limits mass exploitation but targeted spear-phishing or supply chain attacks remain plausible. The vulnerability could also be leveraged in multi-stage attacks against European critical infrastructure or enterprises handling sensitive documents.

The primary mitigation is to upgrade pdfminer.six to version 20251107 or later, where the unsafe deserialization has been addressed. Organizations should audit their environments to identify all instances of pdfminer.six usage, including embedded or indirect dependencies in software stacks. Restricting the processing of PDFs from untrusted or unknown sources can reduce exposure. Implement sandboxing or containerization for PDF processing workflows to contain potential exploitation. Employ network and endpoint detection tools to monitor for anomalous behavior indicative of code execution following PDF processing. Educate users about the risks of opening PDFs from unverified senders. For developers, consider replacing pickle-based deserialization with safer alternatives or validating inputs rigorously before deserialization. Regularly update dependencies and monitor vulnerability disclosures related to pdfminer.six and similar libraries.