xss-cross-site-scripting

xss-cross-site-scripting is a skill for Claude Code, Codex from DorianGallo/hack-skills-local. It costs 36 tokens per session (3,735 once invoked), scanned A, a copy of xss-cross-site-scripting, MIT.

A security playbook for finding and understanding cross-site scripting, or XSS, when user-controlled text reaches web pages or browser code.

In plain words
What is it for?
Assess XSS risks in HTML, attributes, JavaScript, DOM operations, uploads, and applications with multiple rendering contexts.
Why use it?
It helps identify dangerous places where input can be interpreted as HTML or JavaScript, including less obvious rendering paths and bypass techniques.

Skill for Claude CodeCodex

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

Good fit Assess XSS risks in HTML, attributes, JavaScript, DOM operations, uploads, and applications with multiple rendering contexts.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/doriangallo/hack-skills-local/xss-cross-site-scripting
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 DorianGallo/hack-skills-local --skill xss-cross-site-scripting
Clone the repo
git clone --depth 1 https://github.com/DorianGallo/hack-skills-local

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-cross-site-scripting

README.md
[![agentmods](https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/xss-cross-site-scripting/github.svg)](https://agentmods.dev/skills/doriangallo/hack-skills-local/xss-cross-site-scripting)
Your own site
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/xss-cross-site-scripting"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/xss-cross-site-scripting/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-cross-site-scripting

Your own site · 80×15
<a href="https://agentmods.dev/skills/doriangallo/hack-skills-local/xss-cross-site-scripting"><img src="https://agentmods.dev/badge/skills/doriangallo/hack-skills-local/xss-cross-site-scripting.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,735 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 100% copy Near-identical to another mod 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 $0.00036 $0.03735
Opus 5 $0.00018 $0.01868
Sonnet 5 $0.00007 $0.00747
Haiku 4.5 $0.00004 $0.00374

Measured 7d ago against content hash 7ff26b11d7ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

xss-cross-site-scripting 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 7d 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.

Origin

This is a copy

100% identical to xss-cross-site-scripting — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/xss-cross-site-scripting/SKILL.md · 380 lines

How it starts

The opening of the file, as written. The whole thing — 380 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Cross-Site Scripting (XSS) — Expert Attack Playbook

AI LOAD INSTRUCTION: This skill covers non-obvious XSS techniques, context-specific payload selection, WAF bypass, CSP bypass, and post-exploitation. Assume the reader already knows <script>alert(1)</script> — this file only covers what base models typically miss. For real-world CVE cases, HttpOnly bypass strategies, XS-Leaks side channels, and session fixation attacks, load the companion SCENARIOS.md.

Extended Scenarios

Also load SCENARIOS.md when you need:

  • Django debug page XSS (CVE-2017-12794) — duplicate key error → unescaped exception → XSS
  • UTF-7 XSS for legacy IE environments (+ADw-script+AD4-)
  • HttpOnly bypass methodology — proxy-the-browser, session riding, CSRF-via-XSS
  • XS-Leaks side channel attacks — timing oracle, cache probing, performance.now() measurement
  • Session fixation via XSS — pre-set session ID before victim login
  • DOM clobbering techniques for CSP-restricted environments

Advanced Tricks

Also load ADVANCED_XSS_TRICKS.md when you need:

  • mXSS / DOMPurify bypass — namespace confusion, <noscript> parsing differential, form/table restructuring
  • DOM Clobbering — property override via id/name, HTMLCollection, deep property chains
  • Modern framework XSS — React dangerouslySetInnerHTML, Vue v-html, Angular bypassSecurityTrust*, Next.js SSR
  • Trusted Types bypass — default policy abuse, non-TT sinks, policy passthrough
  • Service Worker XSS persistence — malicious SW registration, fetch interception, post-patch survival
  • PDF/SVG/MathML XSS vectors, polyglot payloads, browser-specific tricks
  • XS-Leaks & side channels — timing oracle, frame counting, cache probing, error event oracle

Before broad payload spraying, you can first load:

  • upload insecure files when you need the full upload path: validation, storage, preview, and sharing behavior

Read the full file on GitHub · 380 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 380 lines · 36 tokens per session scan A 7ff26b11d7ef

Subscribe to this mod's changes

xss-cross-site-scripting is a skill published in the GitHub repository DorianGallo/hack-skills-local (5 stars, last pushed 3mo ago), licensed MIT. It adds 36 tokens to every session and 3,735 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to xss-cross-site-scripting, differing in 0 lines, and is treated as a copy.

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