Hardening the UI

Blazor has built-in protections against common web attacks, but you must still follow best practices to keep your enterprise apps safe.

1. Cross-Site Scripting (XSS)

Blazor automatically **HTML-Encodes** all data rendered in the UI. If a user tries to inject <script>alert('pwnd')</script> into a name field, Blazor renders it as literal text, not code. The only danger is if you explicitly use MarkupString to render raw HTML—**never** use this with user-provided data.

2. Cross-Site Request Forgery (CSRF)

Blazor Server uses a built-in Anti-Forgery token mechanism for its SignalR connection. For Blazor WASM apps talking to an API, you should use **Anti-Forgery Cookies** or **CORS** restrictions to ensure that only your app can call your API. Use the [ValidateAntiForgeryToken] attribute on your controllers for added safety.

3. Architect Insight

Q: "What is the most common security slip-up in Blazor?"

Architect Answer: "Leaving **Developer Debugging** endpoints open in production. In Blazor WASM, users can see your DLLs and even decompile them if they try hard enough. Make sure your 'appsettings.json' and 'Authorization' logic don't leak sensitive connection strings or administrative keys to the client-side bundle."