XSS in V0-Generated Components
V0 generates polished React and Next.js components from text and image prompts. While the UI looks production-ready, the generated code sometimes renders user-supplied data unsafely, creating cross-site scripting vectors that persist when developers copy components into their applications.
Scan Your v0 AppHow It Happens
V0 generates individual UI components rather than full applications. When a developer prompts V0 for a "comment section," "user profile card," or "markdown preview," the output focuses on visual fidelity and component structure. If the prompt implies rich text or HTML rendering, V0 may use dangerouslySetInnerHTML to achieve the desired visual output. The risk is amplified by V0's copy-paste workflow. Developers generate a component in V0's interface, copy it into their Next.js project, and wire it up to real data. The component looked safe in V0's preview (which used static sample data), but becomes vulnerable when connected to actual user input. V0 also generates components that interpolate URL parameters into rendered output for features like search results or filtered views. When these components are integrated into a Next.js router, URL parameters become an attack vector for reflected XSS.
Impact
XSS in a V0-generated component executes in the context of the host application. If the host app uses cookies, localStorage tokens, or Next.js session management, the attacker gains access to the authenticated user's session. Because V0 components are designed to be embedded in larger applications, a single vulnerable component can compromise the security of the entire app. The component inherits the parent application's origin, cookies, and permissions. V0 components are widely shared and reused. A vulnerable pattern generated by V0 can propagate across many projects as developers share and fork components, creating a supply-chain-like effect where one bad generation affects multiple applications.
How to Detect
Search V0-generated components for dangerouslySetInnerHTML before integrating them into your project. Check whether any props that flow into dangerouslySetInnerHTML come from user input, URL parameters, or database queries. After integration, test the component by passing XSS payloads through every prop that accepts strings. If the component renders HTML from a prop called content, html, or body, it is likely vulnerable. Vibe App Scanner detects XSS in deployed Next.js applications regardless of whether the vulnerable component was generated by V0, written by hand, or produced by another AI tool.
How to Fix
Review every V0-generated component before copying it into your project. Replace dangerouslySetInnerHTML with safe alternatives: use react-markdown for markdown content, or render text with JSX expressions that auto-escape HTML. If HTML rendering is required, wrap dangerouslySetInnerHTML with DOMPurify.sanitize(). Create a project utility for sanitized HTML rendering so future V0 components can be easily updated. For components that use URL parameters, ensure all router values are treated as untrusted input. Use Next.js's built-in escaping through JSX rather than string interpolation for URL-derived content. Add a CSP header in your Next.js config to restrict script execution. This provides defense-in-depth against XSS in any component, V0-generated or otherwise.
Code Examples
V0-generated rich text component
// Copied from V0 output
export function RichContent({ html }: { html: string }) {
return (
<div
className="prose dark:prose-invert"
dangerouslySetInnerHTML={{ __html: html }}
/>
)
}import DOMPurify from 'dompurify'
export function RichContent({ html }: { html: string }) {
return (
<div
className="prose dark:prose-invert"
dangerouslySetInnerHTML={{
__html: DOMPurify.sanitize(html)
}}
/>
)
}Frequently Asked Questions
Are V0 components safe by default?
V0 components use React's JSX escaping for most text rendering, which is safe. The risk arises when V0 uses dangerouslySetInnerHTML for rich text or HTML content display, which bypasses React's built-in XSS protection.
Does V0 preview catch XSS vulnerabilities?
No. V0's preview uses static sample data that does not contain malicious payloads. Components that appear safe in the preview may be vulnerable when connected to real user input in your application.
Should I audit every V0 component I use?
Yes, review every component before integration. Focus on how dynamic data is rendered. Any component that accepts HTML strings or renders formatted content should be checked for dangerouslySetInnerHTML usage.
Related Security Resources
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