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XSS Vulnerability in Thymeleaf Templates
XSS attacks are possible through template injection. Attacker-controlled input executes JavaScript on victim's browser.
Improper escaping of user input in templates allows script execution.
Common Causes
- Using th:utext instead of th:text (unescaped)
- Raw HTML from database without sanitization
- User input directly in JavaScript context
- th:onclick, th:onhover with user data
How to Fix It
Always use th:text (escapes HTML). Use th:utext only for trusted content. Never put user input in script blocks or event handlers. Sanitize HTML with OWASP Java HTML Sanitizer. Use CSP (Content Security Policy) header. Test with OWASP ZAP.
Real developers can help you.
Matthew Butler
Systems Development Engineer @ Amazon Web Services
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.
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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
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rayush33
JavaScript (React.js, React Native, Node.js) Developer with demonstrated industry experience of 4+ years, actively looking for opportunities to hone my skills as well as help small-scale business owners with solutions to technical problems
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.**
Stanislav Prigodich
15+ years building iOS and web apps at startups and enterprise companies. I want to use that experience to help builders ship real products - when something breaks, I'm here to fix it.
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.
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Yovel Cohen
I got a lot of experience in building Long-horizon AI Agents in production, Backend apps that scale to millions of users and frontend knowledge as well.
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/
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's the difference between th:text and th:utext?
th:text escapes HTML (safe), th:utext outputs raw HTML (unsafe for user input)
How do I sanitize user-provided HTML?
Use OWASP Java HTML Sanitizer library with whitelist approach