Cursor security

HTML Escaping Removed, Creating XSS Vulnerability

After Cursor refactored your template rendering code, HTML escaping was removed or disabled. User input is now rendered as HTML instead of being escaped, creating an XSS vulnerability.

Any user-supplied content could run malicious scripts.

Error Messages You Might See

Script tag executed in user content JavaScript injected Cookie/token stolen Unexpected script execution
Script tag executed in user contentJavaScript injectedCookie/token stolenUnexpected script execution

Common Causes

  1. HTML escaping disabled with dangerouslySetInnerHTML or v-html
  2. innerHTML used instead of textContent
  3. Template escaping turned off
  4. User input rendered without sanitization
  5. Third-party HTML inserted without validation

How to Fix It

Always escape user input in templates. React escapes by default (good). Never use dangerouslySetInnerHTML with user data. Sanitize with DOMPurify if HTML needed. Use Content Security Policy header. Validate and filter input server-side.

Real developers can help you.

Matthew Jordan Matthew Jordan I've been working at a large software company named Kainos for 2 years, and mainly specialise in Platform Engineering. I regularly enjoy working on software products outside of work, and I'm a huge fan of game development using Unity. I personally enjoy Python & C# in my spare time, but I also specialise in multiple different platform-related technologies from my day job. David Olverson David Olverson Solo dev shipping production apps with AI-assisted development. I specialize in rescuing broken Lovable/Bolt/Cursor builds and taking them to production. 10+ apps shipped including SaaS CRMs, gaming platforms, real estate tools, and Discord bots. Stack: Next.js 16, TypeScript, Tailwind CSS, FastAPI, PostgreSQL, Prisma. I use Claude Code with 50+ custom skills for rapid delivery. Average turnaround: 2-4 weeks from broken prototype to production. Jaime Orts-Caroff Jaime Orts-Caroff I'm a Senior Android developer, open to work in various fields Jared Hasson Jared Hasson Full time lead founding dev at a cyber security saas startup, with 10 yoe and a bachelor's in CS. Building & debugging software products is what I've spent my time on for forever Antriksh Narang Antriksh Narang 5 years+ Experienced Dev (Specially in Web Development), can help in python, javascript, react, next.js and full stack web dev technologies. Vlad Temian Vlad Temian 15+ years shipping production infrastructure for startups. Former CTO at qed.builders (acquired by The Sandbox). Cursor ambassador and agentic tooling builder. I've scaled systems, automated deployments, and built observability tools for AI coding workflows. I specialize in taking vibe-coded apps from broken prototype to production-ready: fixing Supabase auth/RLS, Stripe integrations, deployment pipelines, and cleaning up AI-generated spaghetti. I build tools in this space (agentprobe, claudebin, micode) and understand both sides: how AI generates code and why it breaks. https://blog.vtemian.com/ MFox MFox Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking. Mehdi Ben Haddou Mehdi Ben Haddou - Founder of Chessigma (1M+ users) & many small projects - ex Founding Engineer @Uplane (YC F25) - ex Software Engineer @Amazon and @Booking.com ISHANTDEEP SINGH ISHANTDEEP SINGH Senior Software Engineer with 7+ years of experience in React, JavaScript, TypeScript, Next.js, and Node.js. I’ve also worked as a tech lead for startups, owning end-to-end technical execution including architecture, development, scaling, and delivery. I bring a strong mix of hands-on coding, product thinking, and technical leadership, and I’m comfortable building products from scratch as well as improving and scaling existing systems. Krishna Sai Kuncha Krishna Sai Kuncha Experienced Professional Full stack Developer with 8+ years of experience across react, python, js, ts, golang and react-native. Developed inhouse websearch tooling for AI before websearch was solved : )

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Frequently Asked Questions

How do I safely render user HTML?

Sanitize with DOMPurify: DOMPurify.sanitize(userHtml). Removes dangerous tags/attributes. Better than escaping.

What's Content Security Policy?

HTTP header that restricts script sources. Prevents inline scripts, external scripts not from whitelist. Protects against XSS.

Related Cursor Issues

Can't fix it yourself?
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