xss

xss is a skill for Claude Code, Codex from sanjaysaini1952/BugBounty-Arsenal. It costs 0 tokens per session (1,739 once invoked), scanned A, original, MIT.

A web-security testing guide for finding cross-site scripting (XSS), a flaw where user input runs as code in another person's browser.

In plain words
What is it for?
It is for testing reflected, stored, and DOM-based XSS, including inputs, profiles, URL fragments, file uploads, and client-side code.
Why use it?
It gives a structured way to check many input fields, upload points, URLs, and browser-code paths that may handle unsafe input.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It is for testing reflected, stored, and DOM-based XSS, including inputs, profiles, URL fragments, file uploads, and client-side code.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sanjaysaini1952/bugbounty-arsenal/xss
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add sanjaysaini1952/BugBounty-Arsenal --skill xss
Clone the repo
git clone --depth 1 https://github.com/sanjaysaini1952/BugBounty-Arsenal

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for xss

README.md
[![agentmods](https://agentmods.dev/badge/skills/sanjaysaini1952/bugbounty-arsenal/xss/github.svg)](https://agentmods.dev/skills/sanjaysaini1952/bugbounty-arsenal/xss)
Your own site
<a href="https://agentmods.dev/skills/sanjaysaini1952/bugbounty-arsenal/xss"><img src="https://agentmods.dev/badge/skills/sanjaysaini1952/bugbounty-arsenal/xss/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for xss

Your own site · 80×15
<a href="https://agentmods.dev/skills/sanjaysaini1952/bugbounty-arsenal/xss"><img src="https://agentmods.dev/badge/skills/sanjaysaini1952/bugbounty-arsenal/xss.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,739 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.01739
Opus 5 $0.00000 $0.00870
Sonnet 5 $0.00000 $0.00348
Haiku 4.5 $0.00000 $0.00174

Measured 12d ago against content hash 23acc675a76c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

xss scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/hunting/xss/SKILL.md · 108 lines

How it starts

The opening of the file, as written. The whole thing — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.

XSS Hunting Skill — 25 Test Cases

Load when: XSS, cross-site scripting, DOM vulnerability, reflected XSS, stored XSS.

1. Reflected XSS in search bar (easy)

Find every search input on the page. Check max character limits. Submit "><svg/onload=alert(1)> and report whether it reflects unescaped into the DOM. Capture request, response, and rendered HTML.

2. Stored XSS in profile fields (medium)

For every user-editable profile field (name, bio, website, location), submit <img src=x onerror=alert(document.domain)>. Re-render the profile as same user and another user. Report which fields persist the payload and where it executes.

3. DOM XSS via URL fragment (medium)

Crawl all routes and grep client JS for sinks: innerHTML, document.write, eval, setTimeout(string), location, dangerouslySetInnerHTML. For each sink, trace whether location.hash/search/referrer reaches it without sanitization. Report source-to-sink path.

4. XSS via SVG upload (medium)

Upload an SVG containing <script>alert(1)</script> to every file upload endpoint. After upload, fetch the file URL directly and report whether Content-Type is image/svg+xml and whether script tags execute.

5. XSS via PDF / HTML render (hard)

Test if uploaded PDFs or HTML files are served inline (no Content-Disposition: attachment) from same origin. If so, craft a PDF with embedded JS and confirm execution in app origin.

6. XSS via Markdown renderer (medium)

Submit [click](javascript:alert(1)), <details open ontoggle=alert(1)>, and raw HTML to every markdown input. Report which payloads survive the sanitizer.

7. XSS via JSON content-type confusion (hard)

Find endpoints that echo JSON. Force HTML by manipulating Accept headers or appending ?callback= for JSONP. Inject script via reflected parameter.

8. Mutation XSS in sanitizers (hard)

If app uses DOMPurify or sanitize-html, test: <noscript><p title="</noscript><img src=x onerror=alert(1)>">. Report sanitizer version and bypass.

Read the full file on GitHub · 108 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 108 lines · 0 tokens per session scan A 23acc675a76c

Subscribe to this mod's changes

xss is a skill published in the GitHub repository sanjaysaini1952/BugBounty-Arsenal (2 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,739 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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