The interface code is usually sound; the risk sits at the boundary where it meets real data. Because v0 produces frontend components that someone else wires to a backend, the recurring problems are environment variables exposed to the browser through client components, unescaped rendering of user content, and validation that exists only in the form.
v0 is a generative UI tool that produces React and Next.js components from prompts. v0 is frontend-first: it produces interface code that is then wired to a backend separately, so the risks concentrate at that boundary.
These are patterns we look for in code produced this way — not flaws in v0 itself. Each names the check that finds it.
In Next.js, any environment variable prefixed for client access is embedded in the bundle and readable by anyone. Generated components frequently need configuration, and the quickest way to make a value available to a client component is the prefix that also publishes it.
Detected by: Hardcoded API key or secret
Interfaces that display formatted content — a description, a markdown field, an editor preview — reach for the React escape hatch that renders raw HTML. If the content originates from a user and is not sanitised, that escape hatch is a cross-site scripting vector.
Detected by: dangerouslySetInnerHTML
Generated forms include client-side validation because that is what makes the interface feel correct, and it does genuinely improve the experience. It is not a security control: the endpoint behind the form accepts whatever is posted to it, and nothing prevents a caller skipping the form and posting directly with whatever payload they like.
Detected by: Unvalidated request input
UI code is generated against an API that is assumed rather than inspected. When that API is written afterwards, or stubbed so the interface renders, the authorisation the component takes for granted is frequently never implemented on the server — and because the component behaves correctly either way, nothing in testing reveals the gap.
Detected by: Unvalidated request input
Every check named above runs automatically. Free on public repositories, no signup, results in under three minutes — with the file and line for each finding.
As interface code it is generally well-formed and idiomatic. What makes it production ready is the work at the boundary — validating on the server, keeping secrets out of the client bundle, and sanitising anything a user supplied before it is rendered.
Environment variables exposed to the browser. In Next.js the prefix that makes a value available to client code also embeds it in the bundle, and it is the fastest way to make a generated component work. Anything published that way should be treated as public.
It produces the interface for authentication — forms, protected layouts, redirects. Whether authentication is actually enforced depends on the server-side implementation behind it, which is written separately and is where the enforcement has to live.