CVE-2026-104848: Tinypool: Prototype Pollution gadget in worker options leads to Remote Code Execution

tinypool passes worker options to new Worker() by reading them off a plain object whose prototype is Object.prototype. Options the application did not set are resolved through the prototype chain and then passed explicitly to worker_threads.Worker.

Node core ignores Worker options inherited from Object.prototype. By reading them and passing them explicitly, tinypool re-materialises them as own properties and defeats that protection.

Two keys reach code execution:

1. execArgv — polluting Object.prototype.execArgv = ['--require', '/path/to/attacker.js'] causes every pool worker to load the attacker’s script.
2. env — polluting Object.prototype.env = { NODE_OPTIONS: '--require /path/to/attacker.js' } achieves the same via environment injection.