Auth & Client-Side Security
low Severity
Free Check

Cross-Tab Opener Leakage (rel="noopener")

Ensures external links with target="_blank" declare rel="noopener noreferrer" to prevent reverse tab-nabbing.

Test Your Website for Cross-Tab Opener Leakage (rel="noopener")

Run this check along with 90+ automated tests across your domain.

Why It Matters

Without noopener, the opened tab has window.opener access and can navigate your tab to a fraudulent login page.

How We Check This

We scan all <a> tags with target="_blank" and flag any missing rel="noopener" or rel="noreferrer".

How to Fix & Implement

Copy-paste configuration blocks tailored for your web server or edge proxy.

nginx snippet
<a href="https://external.com" target="_blank" rel="noopener noreferrer">Link</a>

Frequently Asked Questions

What is reverse tab-nabbing?

An attack where a newly opened link redirects the parent tab using window.opener.location = "https://phishing.com".