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xss-stored

xss-stored is a skill for Claude Code from securityfortech/hacking-skills. It costs 108 tokens per session (1,592 once invoked), scanned A, original, no licence file.

A guide to finding stored cross-site scripting, where harmful input is saved by a website and later shown to other users as browser code. Common storage points include profiles, comments, forum posts, filenames, and logs.

In plain words
What is it for?
Use it to review input handling and output encoding in web forms, uploads, comments, profiles, and server logs.
Why use it?
It helps identify places where saved user input is displayed without being safely encoded, which can run code in another user's browser.

Skill for Claude Code

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

Part of the web plugin — 28 skills shipped together

not rated 21repo +1 7mo ago A scan 108 tokens no licence

Good fit Use it to review input handling and output encoding in web forms, uploads, comments, profiles, and server logs.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/securityfortech/hacking-skills/xss-stored
View source ↗ securityfortech/hacking-skills
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 securityfortech/hacking-skills --skill xss-stored
Clone the repo
git clone --depth 1 https://github.com/securityfortech/hacking-skills

Made for: Claude Code.

Or install web, the plugin that ships this one along with the rest of its 28 skills.

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-stored

README.md
[![agentmods](https://agentmods.dev/badge/skills/securityfortech/hacking-skills/xss-stored/github.svg)](https://agentmods.dev/skills/securityfortech/hacking-skills/xss-stored)
Your own site
<a href="https://agentmods.dev/skills/securityfortech/hacking-skills/xss-stored"><img src="https://agentmods.dev/badge/skills/securityfortech/hacking-skills/xss-stored/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-stored

Your own site · 80×15
<a href="https://agentmods.dev/skills/securityfortech/hacking-skills/xss-stored"><img src="https://agentmods.dev/badge/skills/securityfortech/hacking-skills/xss-stored.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 108 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,592 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 $0.00108 $0.01592
Opus 5.5 $0.00043 $0.00637
Sonnet 5.5 $0.00022 $0.00318
Haiku 4.5 $0.00011 $0.00159

Measured 2mo ago against content hash 7c1207d12915, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

xss-stored 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 2mo 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 -s -b "SESSION=TOKEN" TARGET/profile | grep -i "storedxss1234"
skills/web/injection/xss-stored/SKILL.md · 115 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. 2mo ago First seen · 115 lines · 108 tokens per session scan A 7c1207d12915

Subscribe to this mod's changes

xss-stored is a skill published in the GitHub repository securityfortech/hacking-skills (21 stars, last pushed 7mo ago), with no licence file. It adds 108 tokens to every session and 1,592 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-08-30.

Security
Related

xss-stored compared with skills from other repositories

xss-stored next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
xss-storedsecurityfortech/hacking-skillsSkill217mo agononeA108Claude Code
imagegenopenai/codexSkill133kyesterdayApache-2.0A113Codex
playwright-climicrosoft/playwrightSkill99kyesterdayApache-2.0A19Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginnersSkill79k4d agoMITA200Claude Code, Codex
systematic-debuggingobra/superpowersSkill313k3d agoMITA21Claude Code
next-cache-components-adoptionvercel/next.jsSkill143kyesterdayMITA95Claude Code
next-partial-prefetching-adoptionvercel/next.jsSkill143kyesterdayMITA103Claude Code