CVE-2023-30583 is a high-severity vulnerability affecting Node.js, specifically related to the experimental permission model introduced in Node.js 20. The vulnerability arises from the fs.openAsBlob() API, which can bypass the intended file system read restrictions when the --allow-fs-read flag is used. This occurs due to a missing permission check within the fs.openAsBlob() function, allowing unauthorized read access to the file system. The permission model is still experimental, but this flaw undermines its security guarantees. The vulnerability affects a broad range of Node.js versions, from 4.0 through 20.0, indicating that the underlying issue or similar API behavior has persisted or been backported across many releases. The CVSS 3.1 score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) reflects that the vulnerability can be exploited remotely without authentication or user interaction, leading to a high impact on confidentiality by allowing unauthorized file reads. Integrity and availability are not impacted. No known exploits are currently in the wild, and no patches have been linked yet, which suggests that mitigation may require updates from the Node.js maintainers once available. The vulnerability is categorized under CWE-284 (Improper Access Control), highlighting the failure to enforce proper permission checks in the API implementation.

For European organizations, this vulnerability poses a significant risk especially for those relying on Node.js for backend services, web applications, or serverless functions. Unauthorized file read access can lead to exposure of sensitive data such as configuration files, credentials, or personal data protected under GDPR. This could result in data breaches, regulatory fines, reputational damage, and potential lateral movement within networks if attackers gain access to internal secrets. Since the vulnerability does not require authentication or user interaction and can be exploited remotely, it increases the attack surface for cloud-hosted Node.js applications and microservices widely used in European enterprises. The broad version range affected means many organizations may be running vulnerable Node.js versions, including legacy systems. The experimental nature of the permission model means that some organizations may have enabled it for testing or early adoption, potentially increasing exposure. Although no exploits are currently known in the wild, the ease of exploitation and high confidentiality impact warrant urgent attention.

1. Immediate mitigation involves auditing Node.js deployments to identify versions in use and whether the experimental permission model with --allow-fs-read is enabled. Disable the experimental permission model or avoid using the --allow-fs-read flag until a patch is available. 2. Restrict network access to Node.js services to trusted internal networks or VPNs to reduce exposure to remote exploitation. 3. Implement strict file system permissions at the OS level to limit the files accessible to Node.js processes, minimizing the impact of unauthorized reads. 4. Monitor logs for unusual file access patterns or attempts to use fs.openAsBlob() in unexpected ways. 5. Stay updated with Node.js security advisories and apply patches promptly once released. 6. Consider using runtime application self-protection (RASP) or Web Application Firewalls (WAF) that can detect and block suspicious API calls. 7. Conduct code reviews and penetration testing focusing on the use of experimental features and file system access in Node.js applications.