Secure Vibe Coding: How to Harden a Vibe-Coded App Before Production

Secure vibe coding comes down to one test: do your trust boundaries still hold when real attack paths are simulated? If Supabase RLS, auth context, or key handling fails under runtime pressure, the app is not production-grade yet, no matter how finished it looks.

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Agentic risk (Cursor, v0, Bolt)

Cursor IDE, Bolt.new, and v0 frequently generate "happy-path secure" flows while skipping negative authorization branches. Ubserve Internal Audit data (2026) shows 18.7% of AI-generated mutation routes accepted cross-tenant object IDs without server-side ownership validation.

What this looks like in production:

• Generated admin/debug route remains enabled in deployed environment.
• Route handler trusts object ID from request without actor-resource binding.
• Supabase RLS allows reads but update/delete policies remain overbroad.

Wrong vs right: BOLA/IDOR-resistant server action

// WRONG: actor is authenticated, but resource ownership is not validated
"use server";
export async function updateProject(input: { projectId: string; name: string }) {
  await db.project.update({
    where: { id: input.projectId },
    data: { name: input.name },
  });
}

// RIGHT: constrain update by actor-owned tenant scope
"use server";
export async function updateProject(input: { projectId: string; name: string }) {
  const session = await requireSession();
  await db.project.updateMany({
    where: { id: input.projectId, tenantId: session.tenantId },
    data: { name: input.name },
  });
}

The Same Bug in a Route Handler, Not Just a Server Action

The server action example above is one shape of the bug. It shows up just as often in plain Next.js route handlers — anywhere a record is fetched by an ID from the URL without checking who's asking:

// WRONG: authenticated actor can fetch any invoice by id
export async function GET(_: Request, { params }: { params: { id: string } }) {
  await requireSession();
  const invoice = await db.invoice.findUnique({ where: { id: params.id } });
  return Response.json(invoice);
}

// RIGHT: enforce actor-tenant ownership before returning data
export async function GET(_: Request, { params }: { params: { id: string } }) {
  const session = await requireSession();
  const invoice = await db.invoice.findFirst({
    where: { id: params.id, tenantId: session.tenantId },
  });
  if (!invoice) return new Response("Not found", { status: 404 });
  return Response.json(invoice);
}

Middleware that only checks session presence won't catch this — it validates that someone is logged in, not that this session owns the record being requested. That check has to live in the handler itself, on every route that returns tenant- or user-scoped data.

Pre-launch hardening sequence

• Verify every mutation endpoint for actor-to-resource authorization.
• Re-run Supabase RLS tests for select/insert/update/delete separately.
• Scan frontend bundles and server logs for key leakage.

Copy-Paste Fix Prompt for Cursor/Claude

Harden my vibe-coded app for production release.
Requirements:
1. Enumerate all write paths (server actions, API routes, RPC calls).
2. For each write path, enforce actor-resource ownership using authenticated tenant/user context.
3. Audit Supabase RLS policies for select/insert/update/delete parity and patch drift.
4. Detect and remove all client-reachable Stripe API Secret Keys and service-role credentials.
5. Return exact patches and tests for negative authorization cases.
Output format:
- Blocking vulnerabilities
- Patch diffs
- Post-fix verification checklist

Production decision rule

If you cannot prove no unauthorized actor can read or mutate tenant data under runtime simulation, delay launch and fix before traffic.

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