Prototype Pollution: How Attackers Corrupt JavaScript's Core Object Template

Prototype Pollution is a JavaScript security vulnerability that allows attackers to modify Object.prototype, the base template from which all JavaScript objects inherit properties. By injecting malicious properties into this shared prototype, an attacker can affect every object created in an application without directly targeting any single one. The attack does not require breaking existing code or cloning credentials — it works by corrupting the underlying factory that shapes all objects. This makes it particularly dangerous, as the impact can propagate silently across an entire application. Understanding how JavaScript's prototype chain works is essential for developers to recognize and defend against this class of attack.