CVE-2023-39333 is a vulnerability in Node.js that arises when the runtime is started with the --experimental-wasm-modules command line option enabled. This feature allows Node.js to import WebAssembly modules with export names. The vulnerability occurs because maliciously crafted export names in these WebAssembly modules can inject arbitrary JavaScript code. This injected code can execute with the privileges of the Node.js process and access data and functions that the WebAssembly module itself cannot normally access, effectively bypassing the intended security boundaries between WebAssembly and JavaScript. The flaw is classified under CWE-94, indicating improper control of code injection. It affects all active Node.js release lines from version 4.0 through 20.0, but only when the experimental flag is used, which is not enabled by default. The CVSS v3.1 base score is 5.3, reflecting a medium severity with network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to integrity (code injection) without confidentiality or availability impact. No patches or known exploits are currently available, but the vulnerability poses a risk to environments that enable this experimental feature, especially in production or exposed systems.

For European organizations, the impact of this vulnerability depends largely on the usage of Node.js with the --experimental-wasm-modules flag enabled. Organizations running Node.js in development or production environments with this flag enabled may be at risk of code injection attacks that could lead to unauthorized code execution and potential integrity compromise of applications. This could allow attackers to manipulate application logic, potentially leading to data manipulation or unauthorized actions within the application context. Although confidentiality and availability impacts are not directly indicated, the integrity compromise could facilitate further attacks or data corruption. Since the vulnerability does not require privileges or user interaction, it could be exploited remotely if the vulnerable Node.js instance is exposed to untrusted inputs or networks. European enterprises relying on Node.js for web services, cloud applications, or serverless functions that experiment with WebAssembly modules should consider this a moderate risk. The absence of known exploits reduces immediate threat but does not eliminate the risk of future exploitation.

1. Disable the --experimental-wasm-modules flag unless absolutely necessary, as this vulnerability only manifests when this feature is enabled. 2. If WebAssembly modules are required, avoid importing untrusted or unauthenticated WebAssembly modules with potentially malicious export names. 3. Monitor Node.js releases and apply security patches promptly once available, as no patches are currently published. 4. Implement strict input validation and sandboxing around WebAssembly module usage to limit exposure. 5. Conduct code reviews and security testing focusing on WebAssembly integration points. 6. Employ runtime application self-protection (RASP) or behavior monitoring to detect anomalous code execution patterns indicative of injection attempts. 7. Restrict network exposure of Node.js services using this feature to trusted internal networks only. 8. Maintain up-to-date inventory of Node.js versions and configurations to quickly identify vulnerable deployments.