Bolt
security
Missing Input Sanitization in Bolt App Forms
Your Bolt.new application accepts user input from forms, URL parameters, and API requests without validating or sanitizing it. This leaves your app vulnerable to cross-site scripting (XSS), HTML injection, data corruption, and other attacks that exploit unfiltered input.
When Bolt generates form handling code, it often passes user input directly to the database or renders it on the page without checking for malicious content. A user could submit a script tag in a comment field, an extremely long string that breaks your layout, or special characters that corrupt your data.
The consequences range from cosmetic issues (broken layouts) to critical security breaches (stolen user sessions, defaced pages, or unauthorized data access). This is one of the most common security gaps in AI-generated applications.
Error Messages You Might See
Warning: Each child in a list should have a unique key prop
Content Security Policy violation: inline script blocked
Unhandled Runtime Error: Objects are not valid as a React child
XSS payload detected in input field
Common Causes
- No server-side validation — Form data is accepted and stored without checking type, length, or format on the backend
- Using dangerouslySetInnerHTML — Bolt generated React components that render user content as raw HTML, enabling XSS
- Client-only validation — Validation exists in the form component but not in the API route, so it can be bypassed with a direct API call
- No Content Security Policy — Missing CSP headers allow injected scripts to execute freely
- Rich text editors without sanitization — WYSIWYG editors that save and display raw HTML from users
- URL parameters used directly — Query string values rendered on the page without escaping
How to Fix It
- Add server-side validation with Zod — Define strict schemas: const schema = z.object({ name: z.string().min(1).max(100), email: z.string().email() }); and validate every API input
- Never use dangerouslySetInnerHTML with user data — Replace it with regular JSX text rendering: {userComment} instead of dangerouslySetInnerHTML={{__html: userComment}}
- Install DOMPurify for HTML content — If you must render HTML, sanitize it: DOMPurify.sanitize(htmlContent, { ALLOWED_TAGS: ['p', 'b', 'i', 'a'] })
- Add Content-Security-Policy headers — Configure CSP to block inline scripts: Content-Security-Policy: default-src 'self'; script-src 'self'
- Validate on both client and server — Share Zod schemas between frontend forms and backend API routes for consistent validation
Real developers can help you.
Victor Denisov
Developer
Richard McSorley
Full-Stack Software Engineer with 8+ years building high-performance applications for enterprise clients. Shipped production systems at Walmart (4,000+ stores), Cigna (20M+ users), and Arkansas Blue Cross. 5 patents in retail/supply chain tech. Currently focused on AI integrations, automation tools, and TypeScript-first architectures.
Dor Yaloz
SW engineer with 6+ years of experience,
I worked with React/Node/Python
did projects with React+Capacitor.js for ios
Supabase expert
Basel Issmail
’m a Senior Full-Stack Developer and Tech Lead with experience designing and building scalable web platforms. I work across the full development lifecycle, from translating business requirements into technical architecture to delivering reliable production systems.
My work focuses on modern web technologies, including TypeScript, Angular, Node.js, and cloud-based architectures. I enjoy solving complex technical problems and helping teams turn product ideas and prototypes into working platforms that can grow and scale.
In addition to development, I often collaborate closely with product managers, business analysts, designers, and QA teams to ensure that solutions align with both technical and business goals.
I enjoy working with startups and product teams where I can contribute both as a hands-on engineer and as a technical partner in designing and delivering impactful software.
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.
hanson1014
Full-stack developer experienced in fixing and deploying AI-generated apps from Lovable, Bolt.new, Cursor, and Replit. I specialize in debugging Supabase integration issues (auth flows, RLS policies, database connections), fixing broken deployments, resolving routing/blank screen problems, and cleaning up messy React/Vite codebases. I also build production apps with the Claude API and have shipped a Mac desktop dev tool (Nexterm from scratch. Based in Hong Kong, fast turnaround.
Kingsley Omage
Fullstack software engineer passionate about AI Agents, blockchain, LLMs.
Caio Rodrigues
I'm a full-stack developer focused on building practical and scalable web applications. My main experience is with **React, TypeScript, and modern frontend architectures**, where I prioritize clean code, component reusability, and maintainable project structures.
I have strong experience working with **dynamic forms, state management (Redux / React Hook Form), and complex data-driven interfaces**. I enjoy solving real-world problems by turning ideas into reliable software that companies can actually use in their daily operations.
Beyond coding, I care about **software quality and architecture**, following best practices for componentization, code organization, and performance optimization.
I'm also comfortable working across the stack when needed, integrating APIs, handling business logic, and helping transform prototypes into production-ready systems.
My goal is always to deliver solutions that are **simple, efficient, and genuinely useful for the people using them.**
Matthew Butler
Systems Development Engineer @ Amazon Web Services
Franck Plazanet
I am a Strategic Engineering Leader with over 8 years of experience building high-availability enterprise systems and scaling high-performing technical teams. My focus is on bridging the gap between complex technology and business growth.
Core Expertise:
🚀 Leadership: Managing and coaching teams of 15+ engineers, fostering a culture of accountability and continuous improvement.
🏗️ Architecture: Enterprise Core Systems, Multi-system Integration (ERP/API/ETL), and Core Database Structure.
☁️ Cloud & Scale: AWS Expert; architected systems handling 10B+ monthly requests and managing 100k+ SKUs.
📈 Business Impact: Aligning tech strategy with P&L goals to drive $70k+ in monthly recurring revenue.
I thrive on "out-of-the-box" thinking to solve complex technical bottlenecks and am always looking for ways to use automation to improve business productivity.
You don't need to be technical. Just describe what's wrong and a verified developer will handle the rest.
Get HelpFrequently Asked Questions
What is the difference between validation and sanitization?
Validation checks that input meets your requirements (correct format, length, type) and rejects bad input. Sanitization modifies input to remove dangerous content while keeping the data. You should do both: validate first, then sanitize what passes.
Does React protect against XSS automatically?
React's JSX auto-escapes content in curly braces ({variable}), which prevents most XSS. However, using dangerouslySetInnerHTML, creating elements via DOM APIs, or setting href/src attributes with user data can still introduce XSS vulnerabilities.