---
title: ToolRouter — Use Case
description: Step-by-step guide for a real-world ToolRouter use case with agent-specific instructions.
url: https://toolrouter.com/tools/pentest/use-cases/test-cors-security
---
# Test CORS Security Configuration

CORS (Cross-Origin Resource Sharing) misconfigurations are among the most common and dangerous web security issues. A misconfigured CORS policy can allow any website to make authenticated requests to your API and read the responses, effectively bypassing the same-origin policy that browsers use to protect users.

The most dangerous misconfiguration is reflecting the Origin header back in Access-Control-Allow-Origin with credentials allowed. This means any website can read authenticated data from your API just by making a fetch request from a malicious page. Other risky configurations include allowing null origins, using overly broad wildcards, or trusting subdomains that could be compromised.

CORS testing verifies that your application only allows cross-origin requests from trusted domains. It checks for origin reflection, null origin handling, wildcard usage, credential exposure, and preflight response consistency. This is critical for any application with an API that handles sensitive data, especially single-page applications where the frontend and API are on different origins.

**Tool:** [Pentest](https://toolrouter.com/tools/pentest)
**Skills:** scan_vulnerabilities

## Agent Guides

- [How to Test CORS Security with Claude](https://toolrouter.com/tools/pentest/use-cases/test-cors-security/claude): Guide for Claude
- [How to Test CORS Security with ChatGPT](https://toolrouter.com/tools/pentest/use-cases/test-cors-security/chatgpt): Guide for ChatGPT
- [How to Test CORS Security with Copilot](https://toolrouter.com/tools/pentest/use-cases/test-cors-security/copilot): Guide for Copilot
- [How to Test CORS Security with OpenClaw](https://toolrouter.com/tools/pentest/use-cases/test-cors-security/openclaw): Guide for OpenClaw
