CVE-2023-23918 is a high-severity privilege escalation vulnerability affecting Node.js versions prior to 19.6.1, 18.14.1, 16.19.1, and 14.21.3. The vulnerability specifically targets the experimental Permissions feature in Node.js, which is enabled via the --experimental-policy flag. This feature is designed to restrict access to certain modules, enforcing a policy that limits what modules can be required by the application. However, due to this vulnerability, an attacker can bypass these permission restrictions by leveraging process.mainModule.require(), a Node.js internal method that allows requiring modules from the main module context. This bypass enables unauthorized access to modules that should have been restricted under the permissions policy. The vulnerability does not require any privileges or user interaction to exploit, and it can be triggered remotely if the affected Node.js application exposes an interface to execute code or load modules dynamically. The CVSS 3.1 base score is 7.5, reflecting a network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, high confidentiality impact, and no impact on integrity or availability. The vulnerability is classified under CWE-863 (Incorrect Authorization). Although no known exploits are reported in the wild, the potential for privilege escalation in Node.js environments using the experimental permissions feature makes this a significant risk. The affected versions span a wide range of Node.js releases, indicating that many applications using older or unpatched versions are vulnerable if they have enabled the experimental permissions feature.

For European organizations, the impact of this vulnerability can be substantial, especially for those relying on Node.js applications that have enabled the experimental permissions feature for module access control. Exploitation could allow attackers to bypass security policies and access sensitive modules or data that should be restricted, potentially leading to unauthorized data exposure or further exploitation within the application environment. This could compromise confidentiality of sensitive business logic or data processed by the Node.js application. Since Node.js is widely used in web services, cloud applications, and backend APIs, a successful exploit could lead to lateral movement within enterprise networks or unauthorized access to critical services. The lack of integrity and availability impact reduces the risk of service disruption or data tampering, but the confidentiality breach alone is critical. European organizations in sectors such as finance, healthcare, and government, which often deploy Node.js in production environments, could face regulatory and compliance consequences under GDPR if sensitive personal data is exposed. Additionally, the vulnerability's exploitation could undermine trust in digital services and lead to reputational damage. Given that the vulnerability requires the experimental permissions feature to be enabled, the impact is somewhat limited to organizations experimenting with or adopting this feature, but those environments must prioritize patching or mitigation.

1. Immediate upgrade of Node.js to patched versions 19.6.1, 18.14.1, 16.19.1, or 14.21.3 or later is the most effective mitigation. 2. If upgrading is not immediately feasible, disable the experimental permissions feature by removing the --experimental-policy flag from Node.js startup parameters to prevent the vulnerable code path from being active. 3. Review and audit Node.js application configurations and code to ensure that the experimental permissions feature is not enabled unintentionally. 4. Implement strict input validation and code execution controls in applications that dynamically load modules or execute code, limiting the attack surface. 5. Employ runtime application self-protection (RASP) or Web Application Firewalls (WAF) that can detect and block attempts to exploit module loading or privilege escalation vectors. 6. Monitor application logs and system behavior for unusual module loading patterns or unauthorized access attempts. 7. Conduct security testing and code reviews focused on module loading and permission enforcement mechanisms. 8. Educate development and operations teams about the risks of using experimental features in production environments without thorough security evaluation.