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.

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 : ) Jen Jacobsen Jen Jacobsen I’m a Full-Stack Developer with over 10 years of experience building modern web and mobile applications. I enjoy working across the full product lifecycle — turning ideas into real, well-built products that are intuitive for users and scalable for businesses. I particularly enjoy building mobile apps, modern web platforms, and solving complex technical problems in a way that keeps systems clean, reliable, and easy to maintain. Matthew Butler Matthew Butler Systems Development Engineer @ Amazon Web Services Pratik Pratik SWE with 15+ years of experience building and maintaining web apps and extensive BE infrastructure 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. Daniel Vázquez Daniel Vázquez Software Engineer with over 10 years of experience on Startups, Government, big tech industry & consulting. 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. 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 Costea Adrian Costea Adrian Embedded Engineer specilizing in perception systems. Latest project was a adas camera calibration system. Matt Butler Matt Butler Software Engineer @ AWS

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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

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