hunt-nextjs

hunt-nextjs is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 75 tokens per session (3,363 once invoked), scanned B, original, MIT.

A security-testing guide for Next.js, a React framework that can render pages on the server and provide application APIs.

In plain words
What is it for?
Use it to inspect image optimization, server actions, middleware, cached pages, React Server Component data, source maps, debug routes, and API endpoints.
Why use it?
It targets framework-specific mistakes such as middleware authentication gaps, unsafe server actions, cache poisoning, server-side request forgery, and leaked server data.

Skill for Claude CodeCodex

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

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is curl --max-time 30 --connect-timeout 10 -s "https://$TARGET/__nextjs_launch-editor?file=../../etc/passwd&line=1".

Good fit Use it to inspect image optimization, server actions, middleware, cached pages, React Server Component data, source maps, debug routes, and API endpoints.

Compare 6 skills from other repositories ↓
About the project

Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.

uphiago/recon-skills · 1,251 stars · on GitHub · hiago.sh

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/uphiago/recon-skills
agentmods
npx agentmods add skills/uphiago/recon-skills/hunt-nextjs

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 hunt-nextjs

README.md
[![agentmods](https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-nextjs/github.svg)](https://agentmods.dev/skills/uphiago/recon-skills/hunt-nextjs)
Your own site
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-nextjs"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-nextjs/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 hunt-nextjs

Your own site · 80×15
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-nextjs"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-nextjs.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,363 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 6 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Privilege Escalation · line 110
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 199
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Privilege Escalation · line 201
    Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.
    Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
  • high Supply Chain · line 214
    Remote code is downloaded and executed. This bypasses code review and could introduce malicious code.
    Fix: Avoid downloading and executing remote scripts. Use trusted packages from PyPI/npm. If remote fetch is required, verify checksums and use HTTPS.
  • medium Data Exfiltration · line 70
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
  • medium Data Exfiltration · line 176
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
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 $0.00075 $0.03363
Opus 5 $0.00037 $0.01682
Sonnet 5 $0.00015 $0.00673
Haiku 4.5 $0.00007 $0.00336

Measured 6d ago against content hash 5c15610be351, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade B, and why

hunt-nextjs 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 6d 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.

Downloads and executes remote codemediumSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

curl --max-time 30 --connect-timeout 10 -s https://$TARGET/ | python3 -c "

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

Makes network callslowCapability

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

curl --max-time 30 --connect-timeout 10 -s https://$TARGET/ | grep -Eo '"buildId":"[^"]+"'
redteam/hunt-nextjs/SKILL.md · 282 lines

How it starts

The opening of the file, as written. The whole thing — 282 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HUNT-NEXTJS — Next.js / SSR Framework Vulnerabilities

Crown Jewel Targets

Next.js-specific bugs that bypass auth or reach SSRF = High/Critical.

Highest-value chains:

  • Server Actions auth bypass — Server Actions enforce auth client-side only → call action ID directly → unauthorized data mutation or exfil
  • Middleware bypass via /_next/static/ — middleware skips static asset paths → protected routes accessible via /_next/data/ IDOR
  • /_next/image SSRF — Image optimizer fetches attacker-controlled URL → internal network scan or cloud metadata
  • ISR stale cache poisoning — inject malicious content into a cached page that gets served to all users
  • RSC payload leakage — React Server Component flight data contains server-side props not meant for client

Attack Surface Signals

/_next/image?url=&w=&q=          Image optimizer — SSRF candidate
/_next/data/BUILD_ID/*.json      Prerendered page data — IDOR candidate
/__nextjs_original-stack-frame   Debug stack frame endpoint
/_next/static/chunks/            JS bundles — source map candidate
/api/                            API routes — standard hunt surface
__NEXT_DATA__ in HTML            SSR props leaked to client
x-nextjs-* response headers      Confirms Next.js

Phase 1 — Fingerprint & Version Detection

# Confirm Next.js and get build ID
curl --max-time 30 --connect-timeout 10 -s https://$TARGET/ | grep -Eo '"buildId":"[^"]+"'
curl --max-time 30 --connect-timeout 10 -sI https://$TARGET/ | grep -i "x-powered-by\|x-nextjs"

# Extract build ID for /_next/data/ paths
BUILD_ID=$(curl --max-time 30 --connect-timeout 10 -s https://$TARGET/ | grep -Eo '"buildId":"\K[^"]+')
echo "Build ID: $BUILD_ID"

# Check Next.js version via package disclosure
curl --max-time 30 --connect-timeout 10 -s https://$TARGET/_next/static/chunks/framework*.js | grep -Eo '"next":"[^"]+"'

# Source map exposure
curl --max-time 30 --connect-timeout 10 -s "https://$TARGET/_next/static/chunks/pages/index.js.map" | head -5
curl --max-time 30 --connect-timeout 10 -s "https://$TARGET/_next/static/chunks/main.js.map" | head -5

Read the full file on GitHub · 282 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. 6d ago First seen · 282 lines · 75 tokens per session scan B 5c15610be351

Subscribe to this mod's changes

hunt-nextjs is a skill published in the GitHub repository uphiago/recon-skills (1,251 stars, last pushed 8d ago), licensed MIT. It adds 75 tokens to every session and 3,363 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it B with 2 findings (downloads and executes remote code, 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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