Nuxt 3 Security Audit Playbook for SaaS in 2025

How to lock down a Nuxt 3 SaaS app without bloat. You’re here because you ship features-not babysit exploits. This playbook gives you audit tactics, code patterns, and shift-left guards that defend your app while staying fast.

Security Landscape in 2025

Modern threats don’t knock-they pivot. Attackers use AI to scan public repos for leaked credentials, misconfigurations, and API endpoints. SaaS is particularly targeted. You’re responsible for your code's exposure even if the infra isn’t yours. External tools make it easier-not optional-monitor your posture continuously.

Nuxt-specific trends:

• The nuxt-security module delivers OWASP headers, rate limiting, and CSP via Helmet middleware.
• Handling state wrong leads to cross-request contamination. Nuxt's useState isolates per-request state safely.
• Sanitize what data flows from server to client using pick and interceptors in useFetch/useAsyncData. Avoid leaking sensitive data blind.

Business Risks and Value

Ignoring security in 2025 isn’t neutral-it’s expensive. Breaches kill trust, compliance fines kill budgets. A single incident slams revenue and sends dev velocity backward.

Security-first saves lives-it keeps you ahead. Proper headers, input validation, and per-route isolation prevent trivial and advanced attacks. Take that seriously.

Technical Breakdown

1. Harden HTTP Surface

Install and configure nuxt-security:

      
export default defineNuxtConfig({
modules: 'nuxt-security',
security: {
headers: {
contentSecurityPolicy: {
directives: {
defaultSrc: "'self'",
scriptSrc: "'self'", "'strict-dynamic'",
imgSrc: "'self'", 'data:',
}
},
frameOptions: 'DENY',
noSniff: true,
},
rateLimiter: { enabled: true, points: 100, duration: 60 },
sizeLimiter: { enabled: true, maxBodySize: 1e6 },
cors: { origin: 'https://your-app.com', methods: 'GET', 'POST' },
hidePoweredBy: true,
}
})

    

This provides OWASP headers, rate limits, request size caps, and CORS by default.

2. State Isolation

Avoid leaking reactive data across requests:

      
export function useUser() {
const safe = useState('user-safe', () => null as User | null)
return safe
}

    

Nuxt request-level isolation prevents state bleed. Do this for cross-request sensitive flags.

3. Secure Data Exposure

Filter server-to-client payloads:

Use pick or interceptors to strip unnecessary data.

4. Auth & Role-based Access

Use HTTP-only cookies and middleware for auth:

      
export default defineEventHandler(async (event) => {
const session = event.node.req.headers.cookie?.match(/session=(^;+)/)?.1
if (!session || !(await validate(session))) {
setResponseStatus(event, 401)
return { error: 'Unauthorized' }
}
return { user: await fetchUser(session) }
})

    

In middleware:

      
export default defineNuxtRouteMiddleware(async (to) => {
const { data, error } = await useFetch('/api/me')
if (error.value || !data.value?.user) return navigateTo('/login')
})

    

Prefer existing modules like nuxt-auth or nuxt-session to avoid footguns.

For role-based authorization:

      
export default defineNuxtRouteMiddleware(async () => {
const { data } = await useFetch('/api/me')
if (data.value?.user.role !== 'admin') return navigateTo('/unauthorized')
})

    

Adjust granularity route-by-route.

5. Secure Middleware Patterns

Middleware should be light, sync, and handled on route-level:

      
export default defineEventHandler((event) => {
console.log('hit', event.node.req.url)
})

    

Avoid heavy operations in global middleware. Prioritize quick checks.

6. Observability & Security CI

Integrate dependency scans, static analysis (SAST), and vulnerability checks into CI. Fail the build on high-severity findings.

Add Lighthouse per-PR security checks (check headers, CSP).

Audit Checklist

Common Pitfalls

Migration Playbook

1. Audit baseline: Scan current headers, identify auth patterns, list all data exposures via API.
2. Add nuxt-security: Enable OWASP headers, limits.
3. Sanitize state and payloads: Isolate state and filter useFetch.
4. Lockdown routes: Apply auth and role middleware.
5. CI integration: Add SAST, header and payload checks.
6. Rollout & monitor: Canary deploy with observability on response delays and security errors.
7. Document & train: Publish guidelines. Make it owner code, not tribal.

Summary

Nuxt 3 gives you surface-level tools to enforce security loudly-use them. You don’t need overengineering. Add security headers, rate limit plugins, state isolation, sanitized payloads, and guarded routes. Automate checks in CI. That’s it. Secure, minimal, and efficient.