CVE-2023-30581 is a vulnerability in Node.js's experimental policy mechanism that allows attackers to bypass module loading restrictions. The issue arises from the use of the __proto__ property in the expression process.mainModule.__proto__.require(), which can be manipulated to require modules outside the scope defined in the policy.json file. This bypass undermines the intended security controls that restrict which modules can be loaded, potentially allowing unauthorized or malicious code execution within Node.js applications. The vulnerability affects all active Node.js release lines that support the experimental policy feature, specifically versions v16, v18, and v20. Since the policy mechanism is experimental, it may not be widely deployed, but for those using it, the impact is significant. The CVSS score of 7.5 (high) reflects the vulnerability's network attack vector, low attack complexity, no privileges required, no user interaction, and a scope limited to the same security domain. The primary impact is on integrity, as unauthorized modules can be loaded, potentially altering application behavior or introducing malicious functionality. No known exploits have been reported in the wild, but the vulnerability was publicly disclosed on November 22, 2023. The weakness is categorized under CWE-862 (Missing Authorization), indicating a failure to properly enforce access control policies. No official patches were listed at the time of disclosure, emphasizing the need for defensive measures by users of the experimental policy feature.

For European organizations, the vulnerability poses a risk primarily to the integrity of Node.js applications that utilize the experimental policy mechanism. Attackers can bypass module loading restrictions, potentially injecting unauthorized or malicious modules that could alter application logic, steal sensitive data, or facilitate further compromise. This is particularly concerning for organizations relying on Node.js for critical backend services, microservices, or serverless functions where module integrity is essential. The lack of required privileges or user interaction lowers the barrier for exploitation, increasing risk exposure. While no availability or confidentiality impact is directly indicated, integrity violations can lead to indirect data breaches or service disruptions. Organizations in sectors such as finance, healthcare, and government, which often deploy Node.js in production environments, may face regulatory and reputational consequences if exploited. The experimental nature of the policy feature may limit exposure, but any usage of this feature should be considered high risk until mitigated.

1. Immediately disable the experimental policy mechanism in Node.js applications until an official patch or update is released that addresses this vulnerability. 2. If disabling the policy feature is not feasible, implement strict code reviews and runtime monitoring to detect unauthorized module loading attempts. 3. Employ alternative module loading restrictions or sandboxing techniques outside of the experimental policy mechanism to enforce module integrity. 4. Keep Node.js versions up to date and monitor official Node.js security advisories for patches related to this CVE. 5. Use application-level security controls such as Web Application Firewalls (WAFs) and Intrusion Detection Systems (IDS) to detect anomalous behavior potentially linked to unauthorized module imports. 6. Educate development teams about the risks of using experimental features in production environments and encourage adherence to stable, well-tested Node.js features. 7. Conduct penetration testing focused on module loading and policy bypass attempts to identify potential exploitation paths.