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.

MFox MFox Full-stack professional senior engineer (15+years). Extensive experience in software development, qa, and IP networking. 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/ 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. Taufan Taufan I’m a product-focused engineer and tech leader who builds scalable systems and turns ideas into production-ready platforms. Over the past years, I’ve worked across startups and fast-moving teams, leading backend architecture, improving system reliability, and shipping products used by thousands of users. My strength is not just writing code — but connecting product vision, technical execution, and business impact. 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 Omar Faruk Omar Faruk As a Product Engineer at Klasio, I contributed to end-to-end product development, focusing on scalability, performance, and user experience. My work spanned building and refining core features, developing dynamic website templates, integrating secure and reliable payment gateways, and optimizing the overall system architecture. I played a key role in creating a scalable and maintainable platform to support educators and learners globally. I'm enthusiastic about embracing new challenges and making meaningful contributions. 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. Prakash Prajapati Prakash Prajapati I’m a Senior Python Developer specializing in building secure, scalable, and highly available systems. I work primarily with Python, Django, FastAPI, Docker, PostgreSQL, and modern AI tooling such as PydanticAI, focusing on clean architecture, strong design principles, and reliable DevOps practices. I enjoy solving complex engineering problems and designing systems that are maintainable, resilient, and built to scale. AUXLE AUXLE I am a Full Stack Developer experienced in building Websites, Web apps and Cross Platform Mobile Apps for Startups and Companies. Rudra Bhikadiya Rudra Bhikadiya I build and fix web apps across Next.js, Node.js, and DBs. Comfortable jumping into messy code, broken APIs, and mysterious bugs. If your project works in theory but not in reality, I help close that gap.

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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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