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.
npx agentmods add skills/allsmog/vuln-scout/nextjs-reactnpx skills add allsmog/vuln-scout --skill nextjs-reactgit clone --depth 1 https://github.com/allsmog/vuln-scoutWrote 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.
[](https://agentmods.dev/skills/allsmog/vuln-scout/nextjs-react)<a href="https://agentmods.dev/skills/allsmog/vuln-scout/nextjs-react"><img src="https://agentmods.dev/badge/skills/allsmog/vuln-scout/nextjs-react.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00060 | $0.01277 |
| Opus 5 | $0.00030 | $0.00639 |
| Sonnet 5 | $0.00012 | $0.00255 |
| Haiku 4.5 | $0.00006 | $0.00128 |
Grade B, and why
nextjs-react scanned grade B 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 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.
Cloud metadata endpointmediumServer-side request forgery
One request to 169.254.169.254 can return temporary IAM credentials.
| Server Action SSRF | Cloud metadata (169.254.169.254) | Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
How it starts
The opening of the file, as written. The whole thing — 174 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Next.js/React Security Analysis
Comprehensive security patterns for Next.js and React applications, covering both client-side and server-side attack surfaces.
Architecture Overview
┌─────────────────────────────────────────────────────────────┐
│ Next.js Application │
├─────────────────────────────────────────────────────────────┤
│ │
│ Client-Side (Browser) Server-Side (Node.js) │
│ ┌──────────────────┐ ┌──────────────────────┐ │
│ │ React Components │ │ Server Components │ │
│ │ Client Actions │◄────────►│ Server Actions │ │
│ │ useEffect/State │ │ Route Handlers │ │
│ └──────────────────┘ │ Middleware │ │
│ │ getServerSideProps │ │
│ └──────────────────────┘ │
│ │
└─────────────────────────────────────────────────────────────┘
Attack Surface Categories
1. Server Actions ("use server")
- SSRF via redirect() with Host header manipulation
- Insecure direct object references
- Missing authentication/authorization
- SQL injection in database operations
2. Route Handlers (app/api/**/route.ts)
- Unauthenticated API endpoints
- Mass assignment vulnerabilities
- Rate limiting bypass
- CORS misconfiguration
3. Server Components
- Data exposure in serialized props
- Sensitive data in
__NEXT_DATA__ - Server-side XSS in rendered content
4. Middleware
- Path-based bypass (normalization)
- Authentication bypass
- Header injection
5. Client Components
- XSS via unsanitized rendering
- Prototype pollution
- Open redirects
Detection Workflow
Step 1: Map the Application
# Find all Server Actions
grep -rn '"use server"' --include="*.ts" --include="*.tsx"
# Find all Route Handlers
find . -path "*/app/api/*" \( -name "route.ts" -o -name "route.js" \)
# Find middleware
find . -name "middleware.ts" -o -name "middleware.js"
# Find page components
find ./app -name "page.tsx" -o -name "page.js"
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.
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.
- 6d ago First seen · 174 lines · 60 tokens per session scan B 18af06d9d13b
nextjs-react is a skill published in the GitHub repository allsmog/vuln-scout (24 stars, last pushed 2mo ago), licensed MIT. It adds 60 tokens to every session and 1,277 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it B with 1 finding (cloud metadata endpoint). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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