v0: what the generator doesn't secure for you
v0 is excellent at one specific job: turning a description or a mockup into polished, accessible, visually consistent React components. That's exactly why it creates a particular risk — the result looks finished, while the security of what happens behind each form was never the question the tool was asked to answer.
A finished-looking component isn't a secured backend
v0 mostly generates frontend code. When a component needs to persist data, two paths come up often: either a direct call to the Supabase client from the React component, or an API route added afterward — sometimes by you, sometimes by asking the AI to "wire the form to the database". Either way, nothing guarantees the question "who is allowed to read or change this row" was ever asked: the component renders perfectly, the data saves, everything looks like it's working — including when any unauthenticated visitor can make the exact same call:
// generated component — the call works, RLS was never checked
const { data } = await supabase
.from('profiles')
.update({ role: 'admin' })
.eq('id', someId);Without an RLS policy that actually restricts this write to the row's owner (or to an authorized role), this call succeeds for anyone holding the public anon key — meaning any visitor.
CORS copy-pasted without a second thought
When an API route gets added to receive data from a v0 component, a permissive CORS setup (Access-Control-Allow-Origin: *) often gets carried over from prototyping examples and is never tightened before going live. On a route that only reads public data, the impact is nil. On a route that returns session- or user-related data, it's a potential leak to any other website.
The fix
Treat every component v0 generates as a frontend that needs a backend thought through separately — not as a feature delivered ready to go. For every table touched by a form or a Supabase call:
ALTER TABLE profiles ENABLE ROW LEVEL SECURITY;
CREATE POLICY "users_update_own_profile" ON profiles
FOR UPDATE
TO authenticated
USING (auth.uid() = id)
WITH CHECK (auth.uid() = id);And if an API route was added alongside it, replace the wildcard with the explicit list of origins that genuinely need to call it.
Details on both pitfalls: Disabled or misconfigured Supabase RLS and Overly permissive CORS.
Got a v0 interface already wired to a real database? Scan the site to check that whatever got connected behind it is actually protected.