Sanitize HTML Input: Prevent XSS, Allow Safe Markup
How to sanitize HTML from user input to prevent XSS. DOMPurify, sanitize-html, and allowlist-based approaches with security tradeoffs explained.
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Tags: text, developer-tools, security
HTML Sanitization: DOMPurify, Sanitize-HTML, and Server-Side Approaches HTML sanitization is the process of taking untrusted HTML input — from a user, an API, or an external source — and removing anything that could cause harm when rendered in a browser. Cross-site scripting (XSS) is the attack vector: an attacker injects tags, event handlers, or specially crafted markup that executes JavaScript in the victim's browser. Sanitization is not the same as escaping (which converts to ). Sanitization preserves safe HTML structure while removing dangerous elements and attributes. --- Why Sanitization Is Hard You might think removing tags is enough. It is not. Here are some of the non-obvious XSS vectors: A proper sanitizer needs to handle all of these, including encoding variations and parser…
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