XSS and Third-Party Scripts: Practical Defenses
Third-party JavaScript is one of the fastest ways to lose control of your frontend security. Analytics, chat widgets, A/B testing tools, tag managers, ad scripts, embedded dashboards — they all run with your page’s privileges unless you isolate them. If one gets compromised, your users see the blast radius, not the vendor. From the browser’s point of view, that script is your code. This is the part many teams get wrong: XSS is not only about your own unsafe innerHTML. It is also about every script you allow to execute in your origin. ...