Security Issues in popular AI Runtimes - Node.js, Deno, and Bun

Introduction

Node.js, Deno, and Bun are the primary runtimes for executing JavaScript and TypeScript in modern applications. They form the backbone of AI backends, serverless deployments, and orchestration layers. Each runtime introduces distinct application security issues. For product security teams, understanding these runtime weaknesses is essential because attacks often bypass framework-level defenses and exploit the runtime directly.

Node.js: Prototype Pollution and Module Injection

Node.js powers most enterprise AI backends. Prototype pollution remains one of the most common attack vectors. Vulnerable libraries such as Lodash (CVE-2019-10744) allow attackers to inject malicious properties into global objects. This leads to privilege escalation inside runtime processes.

Module injection is another major risk. Applications that use require() with unvalidated paths can be tricked into loading malicious modules. In one real incident, an attacker poisoned the npm registry with a typosquatted package (expres instead of express), leading Node.js applications to load a backdoored module that exfiltrated environment variables.

Deno: Permission Model Misuse

Deno was designed with a stricter permission model than Node.js. Developers must explicitly grant file, network, or environment variable access. In practice, many teams disable these controls with the --allow-all flag for convenience. This reintroduces Node.js–style risks and undermines Deno’s security design. In test deployments, attackers exploited over-permissive Deno configurations to access local files containing API keys.

Bun: Immature Ecosystem and WASM Risks

Bun is the newest runtime and aims to outperform Node.js and Deno. Its ecosystem is immature, which means fewer security audits and less hardened libraries. Bun also integrates deeply with WebAssembly (WASM). Exploits in WASM runtimes have demonstrated sandbox escapes, enabling arbitrary code execution. In one proof-of-concept, malformed WASM payloads in Bun caused memory corruption, highlighting the risks of relying on an immature runtime for production AI workloads.

MITRE ATT&CK Mapping

Conclusion

Node.js, Deno, and Bun are powerful but not secure by default. Node.js remains vulnerable to prototype pollution and module injection. Deno’s permission system is often bypassed through developer misconfiguration. Bun introduces WASM-specific risks and suffers from ecosystem immaturity. For product security teams, runtime-level defenses such as strict configuration policies, dependency validation, and runtime anomaly monitoring are critical to securing AI applications.

References

• npm, Inc. (2018). event-stream incident report. npm Blog. https://blog.npmjs.org/post/180565383195/details-about-the-event-stream-incident
  
• OWASP. (2021). JavaScript prototype pollution. OWASP Foundation. https://owasp.org/www-community/vulnerabilities/Prototype_Pollution
  
• MITRE ATT&CK®. (2024). ATT&CK Techniques. MITRE. https://attack.mitre.org/
• SecurityWeek. (2022, July 5). New vulnerabilities found in WebAssembly runtimes. SecurityWeek. https://www.securityweek.com