How to Secure Your v0 App
v0 by Vercel generates beautiful React components and full applications. While the UI code is generally safe, the generated API routes, data fetching, and authentication patterns need security review. This guide covers how to harden your v0-generated application.
Find security issues automatically before attackers do.
Follow These Steps
Review generated API routes for security issues
v0 generates Next.js API routes that may lack input validation, authentication checks, and proper error handling. Review every file in app/api/ directory.
// Check every API route has auth + validation
// app/api/posts/route.ts
import { auth } from '@/auth'
import { z } from 'zod'
export async function POST(req: Request) {
const session = await auth()
if (!session) {
return Response.json({ error: 'Unauthorized' }, { status: 401 })
}
const body = await req.json()
const parsed = PostSchema.safeParse(body)
if (!parsed.success) {
return Response.json({ error: 'Invalid input' }, { status: 400 })
}
// Process validated data
}Move API keys to environment variables
If v0 generated code that calls external APIs, ensure credentials are in environment variables. Vercel provides a secure environment variables system.
# In Vercel dashboard: Settings > Environment Variables
# Add your secrets there, not in code
# For local development, use .env.local
OPENAI_API_KEY=sk-proj-...
DATABASE_URL=postgresql://...
# Access in server-side code only
const key = process.env.OPENAI_API_KEYNever prefix secrets with NEXT_PUBLIC_ as this exposes them to the browser.
Add security headers via next.config.js
v0 does not generate security headers by default. Add them to protect against common web attacks.
// next.config.js
/** @type {import('next').NextConfig} */
const nextConfig = {
async headers() {
return [{
source: '/(.*)',
headers: [
{ key: 'X-Content-Type-Options', value: 'nosniff' },
{ key: 'X-Frame-Options', value: 'DENY' },
{ key: 'Referrer-Policy', value: 'strict-origin-when-cross-origin' },
{ key: 'Strict-Transport-Security', value: 'max-age=63072000; includeSubDomains; preload' },
{ key: 'Permissions-Policy', value: 'camera=(), microphone=(), geolocation=()' }
]
}]
}
}
module.exports = nextConfigImplement authentication with Auth.js
If your v0 app needs user accounts, integrate Auth.js rather than building custom auth. It integrates natively with Next.js and Vercel.
// auth.ts
import NextAuth from 'next-auth'
import GitHub from 'next-auth/providers/github'
export const { handlers, auth, signIn, signOut } = NextAuth({
providers: [GitHub],
callbacks: {
authorized({ auth, request }) {
return !!auth?.user
}
}
})
// middleware.ts - protect routes
export { auth as middleware } from '@/auth'
export const config = { matcher: ['/dashboard/:path*'] }Protect Server Actions
v0 generates Server Actions that may not have authentication or input validation. Every Server Action that modifies data needs both.
'use server'
import { auth } from '@/auth'
import { z } from 'zod'
const UpdateProfileSchema = z.object({
name: z.string().min(1).max(100),
bio: z.string().max(500).optional()
})
export async function updateProfile(formData: FormData) {
const session = await auth()
if (!session?.user?.id) throw new Error('Unauthorized')
const data = UpdateProfileSchema.parse({
name: formData.get('name'),
bio: formData.get('bio')
})
// Update database with validated data
}Secure database queries
If v0 generated database code with Prisma or Drizzle, verify queries are properly scoped to the authenticated user.
// Always scope queries to the authenticated user
const posts = await db.query.posts.findMany({
where: eq(posts.userId, session.user.id)
})
// Never allow user to specify arbitrary IDs without ownership check
export async function deletePost(postId: string) {
const session = await auth()
const post = await db.query.posts.findFirst({
where: and(
eq(posts.id, postId),
eq(posts.userId, session!.user.id) // ownership check
)
})
if (!post) throw new Error('Not found')
await db.delete(posts).where(eq(posts.id, postId))
}Deploy and scan on Vercel
Deploy your secured app to Vercel and run a VAS scan to verify all security measures are working correctly in production.
Vercel automatically provides HTTPS and edge network protection. Focus your efforts on application-level security.
What You'll Achieve
Your v0 app now has authentication on all protected routes, input validation on API routes and Server Actions, security headers, proper secret management, and scoped database queries. The application is production-ready from a security standpoint.
Common Mistakes to Avoid
Mistake
Not protecting Server Actions with authentication
Fix
Every Server Action that modifies data must check the user session. Server Actions are public endpoints even though they feel like internal functions.
Mistake
Using NEXT_PUBLIC_ prefix for secret keys
Fix
NEXT_PUBLIC_ exposes variables to the browser bundle. Only use it for truly public values like your app URL. Keep secrets as server-only env vars.
Mistake
Accepting user-provided IDs without ownership verification
Fix
Always verify the authenticated user owns the resource before allowing read, update, or delete operations.
Frequently Asked Questions
Is v0 generated code secure?
v0 generates clean React and Next.js code, but security features like authentication, input validation, and security headers need to be added. The UI components themselves are generally safe.
Does Vercel add security headers automatically?
Vercel provides HTTPS and some basic protections, but does not add application security headers like X-Content-Type-Options, CSP, or X-Frame-Options. You must configure these in next.config.js.
Are Server Actions in v0 apps secure?
Server Actions run on the server but are exposed as public HTTP endpoints. They need authentication checks and input validation just like API routes. Never assume they are internal-only.
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