Kleared

v0 security audit

Using v0? Your UI might look secure — but isn’t.

v0 generates excellent React components. Components are not security boundaries. The most common v0 problem we see is gorgeous UI shipped with backend logic that trusts whatever the frontend sends.

Get a Launch Audit — $299See how it works →

Common problems

What we keep finding in v0 codebases.

  • Frontend-only protection

    Auth gates, role checks, and visibility rules live entirely in the React tree. The underlying API endpoints have no idea any of this exists.

    Example
    {role === "admin" && <DeleteButton />} hides the button. POST /api/things/42 deletes anyway.

  • Missing backend enforcement

    v0&rsquo;s example handlers often skip auth entirely or use placeholder middleware that never made it to production-grade.

  • Dangerous form handling

    Form submissions trust the shape of their payload. Type assertions get rewritten to runtime trust. Unexpected fields get persisted.

  • Exposed internal logic

    Helper utilities and internal functions get re-exported to the client because v0 needs them for a preview. They become attackable.

Prompt fixes

What to tell the model.

Paste these into your next conversation. They steer generation toward safer defaults — but they aren't a substitute for review.

  • For: Frontend-only protection

    “Treat the frontend as public. Re-check identity, role, and ownership server-side for every action — never rely on conditional rendering as security.”

  • For: Missing backend enforcement

    “Validate the authenticated user inside every API route handler and server action. Don&rsquo;t assume middleware ran — confirm it.”

  • For: Dangerous form handling

    “Validate every form payload server-side with a strict schema (zod, valibot, or similar). Reject unknown fields explicitly.”

  • For: Exposed internal logic

    “Isolate sensitive business logic behind server boundaries. Never re-export internal helpers to client components.”

Manual verification

The v0 checklist.

Run through each item by hand before you ship. If anything is unclear, treat it as a red flag, not a green light.

  • Hit every action endpoint directly with curl from an unauthenticated session.
  • Sign in as a low-privilege user and call admin endpoints by URL.
  • Submit forms with extra fields and confirm they&rsquo;re rejected.
  • Search for &lsquo;use client&rsquo; modules importing server-only utilities.
  • Confirm every server action calls auth() or its equivalent before doing work.

If issues are already live

Damage control, in order.

If you suspect any of the above already shipped to real users, work the list top-to-bottom. Don’t skip rotation.

  1. 1Add server-side auth checks to every route handler before announcing the fix.
  2. 2Strict-validate every form payload with a schema.
  3. 3Audit client modules for accidental imports of server-only code.
  4. 4Rotate any secrets that might have been embedded in client bundles.
  5. 5Re-test every endpoint with an unauthenticated and a low-privilege session.

Why AI-generated fixes still fail

The model that wrote the bug rarely sees it.

Same blind spots

The patterns that produced the vulnerability are baked into the model's training. Asking it to audit itself reproduces the same assumptions.

Context windows lie

The model sees the file you paste, not your auth middleware, your RLS policies, or the route you forgot to protect. It can't review what it can't see.

Confidence ≠ correctness

AI fixes look polished and read well. That's a signal of fluency, not of safety. Real verification needs a human who can hit the endpoint.

Don’t ask AI to audit AI

You wouldn’t let an intern grade their own homework.

Most builders type “is this secure?” back into the same chat that wrote the code. You need independent verification — someone whose context isn’t poisoned by what just got generated. That’s Kleared.

Beautiful UI does not equal secure software.

Kleared verifies the part users can’t see — server actions, route handlers, schema validation — and opens fix-PRs that match the rest of your codebase.

Let Kleared audit it before users do →How the pipeline works

Before you launch

Run a real human security review.

Not another prompt. Kleared checks the boring stuff that breaks production:

  • auth
  • permissions
  • secrets
  • uploads
  • database exposure
  • API security
  • payment flows
  • production configs

So you can ship without guessing.

Get your Launch Audit — $299