XSS - Mutation Scanner
Tests for mutation XSS (mXSS) that bypasses sanitization through browser parsing quirks.
What is XSS - Mutation?
Mutation XSS (mXSS) exploits differences between how sanitizers parse HTML and how browsers actually render it. When sanitized HTML is inserted into the DOM, the browser may 'mutate' it during parsing in unexpected ways, creating executable JavaScript from seemingly safe content.
Why is This Important?
mXSS bypasses many client-side sanitization libraries because the payload looks safe during sanitization but becomes dangerous after browser parsing. This affects popular libraries like DOMPurify (older versions) and has impacted major sites like Google.
How It Works
1. Web Crawling
Intelligent crawling discovers all endpoints, forms, parameters, and dynamic content across your web application.
2. Payload Injection
AI-powered payloads test each input vector for web vulnerabilities with context-aware attack patterns.
3. Response Analysis
Advanced analysis detects vulnerability signatures in responses, confirming exploitability with proof-of-concept.
Key Capabilities
Industry-leading web security testing powered by AI, trusted by security teams worldwide for accurate vulnerability detection.
- Deep web crawling with JavaScript rendering support
- Context-aware payload generation for each parameter
- False positive elimination through response analysis
- OWASP Top 10 and CWE compliance mapping
- Seamless CI/CD and DevSecOps integration
Frequently Asked Questions
How does mutation XSS work?
Browsers parse and 'fix' malformed HTML in ways that differ from sanitizer parsing. A payload that passes sanitization may be restructured by the browser into executable code.
What causes HTML mutation?
Browser HTML error correction, namespace handling (SVG/MathML), character encoding changes, and parser quirks can transform safe-looking HTML into dangerous content.
Are sanitization libraries safe?
Modern versions of DOMPurify and similar libraries are mXSS-aware, but keeping them updated is critical. Custom sanitizers are especially risky.
How do I prevent mutation XSS?
Use well-maintained sanitization libraries (DOMPurify, sanitize-html), keep them updated, and consider using textContent instead of innerHTML when possible.
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