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xss-prevention

Provide encoding, sanitization, and CSP guidance to mitigate frontend XSS risks.

Updated Mar 29, 2026
Search Tags:#security#frontend#xss#sanitization#csp#encoding
One-click install
npx skills add https://github.com/marquesfelip/agents-and-skills --skill xss-prevention-marquesfelip
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: xss-prevention
Source: https://github.com/marquesfelip/agents-and-skills/tree/main/skills/xss-prevention
Command: npx skills add https://github.com/marquesfelip/agents-and-skills --skill xss-prevention-marquesfelip

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

XSS vulnerabilities in web applications by providing encoding, sanitization, and CSP guidance.

Core Features & Use Cases

  • Output encoding guidelines for HTML, JS, and URLs
  • Sanitization strategies using DOMPurify and framework-safe patterns
  • CSP configuration and safe integration guidance across React, Vue, Angular, and server-side rendering for both frontend and backend contexts
  • Use Case: Audit rendering of user input in a component to prevent unsafe innerHTML

Quick Start

Analyze a frontend component rendering user input and implement HTML encoding, DOM sanitization, and a CSP header.

Frequently Asked Questions about xss-prevention

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I prevent XSS vulnerabilities when rendering user-supplied HTML in web applications?▼

Preventing XSS requires applying context-aware output encoding for HTML, JavaScript, and URLs, alongside DOM sanitization and Content Security Policy (CSP) configuration. This approach mitigates frontend risks across server-rendered pages, SPA components, and API responses.

What's the best way to sanitize user input in React, Vue, or Angular components?▼

Sanitizing user input in React, Vue, and Angular involves using framework-safe patterns alongside libraries like DOMPurify. This ensures safe DOM manipulation and prevents unsafe innerHTML rendering when processing user-supplied HTML.

How do I configure Content Security Policy headers for a single page application?▼

Configuring CSP for a single page application involves setting response headers that restrict resource loading and script execution. Integrating CSP alongside framework-safe rendering patterns provides defense-in-depth against XSS attacks.

When do I need output encoding versus DOM sanitization for XSS protection?▼

Output encoding is needed when rendering user data in HTML, JavaScript, or URL contexts to escape special characters, while DOM sanitization cleans user-supplied HTML before insertion. Combining both ensures comprehensive XSS prevention across different rendering vectors.

Why does using innerHTML cause XSS vulnerabilities in frontend components?▼

Using innerHTML causes XSS vulnerabilities because it executes embedded scripts when rendering user-supplied HTML directly into the DOM. Auditing components to implement HTML encoding and DOM sanitization prevents this unsafe execution.

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