xss-dom

xss-dom is a skill for Claude Code, Codex from blacklanternsecurity/red-run. It costs 15 tokens per session (2,712 once invoked), scanned A, original, GPL-3.0.

A security-testing guide for DOM-based cross-site scripting (XSS), where browser-side code turns unsafe page data into executable content.

In plain words
What is it for?
Use it to inspect client-side routes, URL fragments, and JavaScript handling of untrusted input.
Why use it?
It helps authorized testers find XSS that happens in the browser without requiring the server to store or reflect the payload.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it to inspect client-side routes, URL fragments, and JavaScript handling of untrusted input.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/blacklanternsecurity/red-run/xss-dom
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 blacklanternsecurity/red-run --skill xss-dom
Clone the repo
git clone --depth 1 https://github.com/blacklanternsecurity/red-run

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-dom

README.md
[![agentmods](https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/xss-dom.svg)](https://agentmods.dev/skills/blacklanternsecurity/red-run/xss-dom)
Your own site
<a href="https://agentmods.dev/skills/blacklanternsecurity/red-run/xss-dom"><img src="https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/xss-dom.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,712 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00015 $0.02712
Opus 5 $0.00008 $0.01356
Sonnet 5 $0.00003 $0.00542
Haiku 4.5 $0.00002 $0.00271

Measured 4d ago against content hash 75c3fc761131, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

xss-dom scanned grade A with 1 finding 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 4d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- **curl is insufficient** for DOM XSS — it doesn't execute JavaScript, so it
skills/web/xss-dom/SKILL.md · 381 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 4d ago First seen · 381 lines · 15 tokens per session scan A 75c3fc761131

Subscribe to this mod's changes

xss-dom is a skill published in the GitHub repository blacklanternsecurity/red-run (267 stars, last pushed 5mo ago), licensed GPL-3.0. It adds 15 tokens to every session and 2,712 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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