v0 security: what to check before launching a v0 app
How secure is v0?
v0 generates Next.js interfaces, and it's strong at the frontend. The security risk appears when you wire that UI to data: a secret stored with a NEXT_PUBLIC_ prefix is exposed in the browser, API routes ship reachable by default, and a Supabase backend added later often has row-level security off.
v0 (by Vercel) turns prompts into Next.js UI and components. On its own it's frontend, but real apps connect it to APIs and databases, and that wiring is where the exposure patterns show up.
The common risks in v0 apps
Secrets exposed via NEXT_PUBLIC_
In Next.js, any env variable prefixed NEXT_PUBLIC_ is bundled into the browser. A key stored that way is readable by anyone.
Unprotected API routes
A route in app/api/ is public the moment it deploys; generated handlers sometimes lack an auth check.
Supabase RLS off
When a v0 UI is connected to Supabase, tables are frequently left without row-level security.
Client-side-only auth
Hiding a page in the UI isn't access control; the underlying data or endpoint can still be reached directly.
How to check your v0 app
- Make sure no real secret uses the NEXT_PUBLIC_ prefix.
- Confirm each API route checks auth server-side, not just in the UI.
- Enable RLS on every Supabase table and verify logged-out access is blocked.
- Test private routes and endpoints while signed out — they should return 401/403.
Scan your v0 app before you launch
SafeLaunch checks your repo and live site in about 30 seconds and gives you a prompt to paste back into v0 to fix each finding.
v0 security FAQ
Is v0 secure?+–
v0 generates solid Next.js UI; the risk comes from how it's wired to data — NEXT_PUBLIC_ secret exposure, open API routes and missing RLS. Check those before launch.
Why is my v0 API key exposed?+–
It's almost certainly stored with a NEXT_PUBLIC_ prefix, which bundles it into the browser. Move it to a server-only variable and rotate it.
How do I scan a v0 app?+–
A SafeLaunch scan checks the repo and live site for exposed secrets, unprotected routes and RLS gaps, with a fix prompt for each finding.