CVE-2024-53924 is a critical remote code execution vulnerability affecting Pycel, an open-source Python library used for evaluating Excel spreadsheet formulas. The vulnerability exists in Pycel versions up to 1.0b30 when processing untrusted spreadsheet files. Specifically, the flaw arises from the unsafe evaluation of crafted formulas within spreadsheet cells. An attacker can embed malicious code within a formula, such as an expression starting with =IF(A1=200, eval("__import__('os').system(...")), which Pycel will execute during formula evaluation. This leads to arbitrary code execution on the host system without requiring any authentication or user interaction. The vulnerability is classified under CWE-94 (Improper Control of Generation of Code), indicating that Pycel fails to properly sanitize or restrict code execution from spreadsheet content. The CVSS v3.1 base score is 9.8 (critical), reflecting the high impact on confidentiality, integrity, and availability, combined with ease of exploitation over the network. Since Pycel is a Python library primarily used in data processing, analytics, and automation workflows involving Excel files, any system or service that uses Pycel to parse or evaluate untrusted spreadsheets is at risk. Exploitation could allow attackers to execute arbitrary system commands, potentially leading to data theft, system compromise, or disruption of services. No patches or vendor mitigations are currently listed, and no known exploits in the wild have been reported as of the publication date (April 17, 2025).

For European organizations, the impact of CVE-2024-53924 is significant, especially for sectors relying heavily on data analytics, financial modeling, or automated spreadsheet processing using Python environments. Organizations in finance, manufacturing, research, and government that integrate Pycel into their data pipelines could face severe risks including unauthorized access to sensitive data, disruption of critical business processes, and potential lateral movement within networks. The ability to execute arbitrary code remotely without authentication means attackers can compromise systems at scale if untrusted spreadsheets are processed automatically. This could lead to data breaches, ransomware deployment, or sabotage of operational technology. Additionally, the lack of patches increases the window of exposure, potentially impacting compliance with European data protection regulations such as GDPR if personal data is compromised. The vulnerability also poses risks to cloud service providers and managed service providers in Europe that offer spreadsheet processing or automation services using Pycel, as a single malicious spreadsheet could compromise entire environments.

1. Immediately audit all systems and workflows that utilize Pycel for spreadsheet formula evaluation, especially those processing untrusted or external Excel files. 2. Implement strict input validation and sanitization to block or quarantine spreadsheets containing suspicious or complex formulas before processing. 3. Where possible, isolate Pycel execution environments using containerization or sandboxing to limit the impact of potential code execution. 4. Replace or supplement Pycel with safer spreadsheet processing libraries that do not evaluate formulas or that have built-in protections against code injection. 5. Monitor logs and system behavior for unusual command executions or process spawning originating from spreadsheet processing components. 6. Educate users and administrators about the risks of opening or processing untrusted spreadsheet files, emphasizing the dangers of automated processing without validation. 7. Develop and deploy custom detection rules in endpoint detection and response (EDR) solutions to flag suspicious eval() or os.system() calls within Python processes. 8. Engage with the Pycel community or maintainers to track the release of patches or safer versions and plan for timely updates once available.