Individual skill

prototype-pollution

Prototype pollution testing for JavaScript stacks. Use when user input is merged into objects (query parsers, JSON bodies, deep assign), when configuring libraries via untrusted keys, or when hunting RCE gadgets via polluted Object.prototype in Node or the browser.

skills/prototype-pollution/SKILL.md

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# SKILL: Prototype Pollution — Expert Attack Playbook

> **AI LOAD INSTRUCTION**: Expert prototype pollution for client and server JS. Covers `__proto__` vs `constructor.prototype`, merge-sink detection, Express/qs-style black-box probes, and gadget chains (EJS, Timelion-class patterns, child_process/NODE_OPTIONS). Assumes you know object spread and prototype inheritance — focus is on **parser behavior** and **post-pollution sinks**.

Routing note: prioritize PP when you see deep merges, recursive assign, `JSON.parse` followed by `Object.assign`, or URL queries converted to nested objects.

## 0. QUICK START

### Client-side first probes

```text
#__proto__[polluted]=1
#__proto__[polluted]=polluted
#constructor[prototype][polluted]=1