XSS in Cursor-Generated Code
Cursor accelerates development with AI-powered code generation, but its suggestions don't always account for security context. XSS vulnerabilities appear when Cursor generates frontend code that handles user input without proper sanitization.
Scan Your Cursor AppHow It Happens
Cursor generates code based on the surrounding context in your editor. When you ask it to create a component that displays user content, it optimizes for functionality. If the existing codebase already uses dangerouslySetInnerHTML or innerHTML, Cursor follows that pattern and propagates the vulnerability to new components. Cursor's autocomplete also introduces XSS when developers accept suggestions without reviewing them carefully. A common scenario: the developer writes a function to display a comment, Cursor suggests using innerHTML for formatting, and the developer tabs to accept without noticing the security implication. Unlike no-code builders, Cursor apps are written by developers who could catch these issues. But the speed of AI-assisted coding means less manual review per line of code, and XSS vectors slip through during rapid iteration.
Impact
XSS in Cursor-generated code has the same severity as any other XSS vulnerability: session hijacking, data theft, account takeover, and defacement. The difference is that Cursor-built apps are often more complex and handle more sensitive data than no-code alternatives. Because Cursor is used by professional developers building production applications, the stakes are higher. These apps often process payments, store personal data, and integrate with enterprise systems. A single XSS vulnerability can compromise an entire business. Additionally, Cursor-generated code tends to be maintained over time rather than rebuilt, meaning XSS vulnerabilities can persist for months or years if not caught early.
How to Detect
Search your codebase for dangerouslySetInnerHTML, innerHTML, document.write, and v-html (for Vue). Review every instance to verify the input is sanitized before rendering. Use a static analysis tool like ESLint with security plugins (eslint-plugin-security, eslint-plugin-react with no-danger rule) to automatically flag unsafe patterns in code that Cursor generates. Vibe App Scanner analyzes the deployed application and tests for both reflected and stored XSS patterns, catching vulnerabilities that static analysis might miss because they span multiple components.
How to Fix
Configure ESLint to warn on dangerouslySetInnerHTML and innerHTML usage. This catches unsafe Cursor suggestions before they reach production. Create a sanitization utility in your project that wraps DOMPurify. When Cursor sees this utility in your codebase, it's more likely to suggest using it for new components. Review all Cursor suggestions that involve rendering dynamic content. Look specifically for any pattern that converts strings to HTML rather than text. Implement Content Security Policy headers that block inline scripts. This stops XSS exploitation even if a sanitization step is missed somewhere in the codebase.
Code Examples
Cursor-suggested content rendering
// Cursor autocomplete suggestion
function UserPost({ content }: { content: string }) {
return (
<article
dangerouslySetInnerHTML={{ __html: content }}
/>
)
}import { sanitize } from '@/lib/sanitize' // project utility
function UserPost({ content }: { content: string }) {
return (
<article
dangerouslySetInnerHTML={{
__html: sanitize(content)
}}
/>
)
}
// @/lib/sanitize.ts
import DOMPurify from 'dompurify'
export const sanitize = (html: string) =>
DOMPurify.sanitize(html)Frequently Asked Questions
Does Cursor introduce more XSS than manual coding?
Not necessarily more, but faster. Cursor generates code at a pace that makes it harder to review every line. The XSS patterns it introduces are standard (innerHTML, dangerouslySetInnerHTML), but they appear more frequently because developers accept suggestions quickly.
Can I configure Cursor to avoid unsafe patterns?
You can add security-focused ESLint rules to your project and include security guidelines in your .cursorrules file. Cursor respects linting errors and project conventions when generating suggestions.
Are Cursor apps more vulnerable than hand-coded apps?
Cursor apps have similar vulnerability types but potentially more instances because of the speed of code generation. The key difference is review quality: AI-generated code needs the same security review as human-written code, but often receives less.
Related Security Resources
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