cors-misconfig

Name: cors-misconfig
Availability: InStock
Author: SecurityforTech

Detect and exploit CORS misconfigurations in web applications.

6|1|Updated Mar 9, 2026

Search Tags:#vulnerability #penetration testing #web security #cors #misconfiguration #data exfiltration

Ready to run

npx skills add https://github.com/securityfortech/hacking-skills --skill cors-misconfig

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: cors-misconfig
Source: https://github.com/securityfortech/hacking-skills/tree/main/skills/web/client-side/cors-misconfig
Command: npx skills add https://github.com/securityfortech/hacking-skills --skill cors-misconfig

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps identify and exploit Cross-Origin Resource Sharing (CORS) misconfigurations, which can lead to sensitive data leakage and security vulnerabilities.

Core Features & Use Cases

Detect Origin Reflection: Identifies servers that improperly echo the Origin header.
Identify Wildcard Issues: Detects overly permissive Access-Control-Allow-Origin: * combined with credentialed requests.
Exploit Null Origin: Tests for acceptance of null origins, often exploitable via sandboxed iframes.
Use Case: A pentester can use this skill to find and demonstrate how an attacker could read sensitive API responses from a victim's browser due to a misconfigured CORS policy.

Quick Start

Test the target URL for CORS misconfigurations by sending a request with an attacker-controlled origin.

Frequently Asked Questions about cors-misconfig

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

FAQPage Schema

How do I detect CORS misconfigurations like origin reflection in web applications?▼

You can test for CORS misconfigurations by sending a request with an attacker-controlled origin to the target URL. This detects servers improperly reflecting the Origin header, potentially allowing sensitive data exfiltration from a victim's browser.

What is a CORS null origin vulnerability and how does it expose sensitive data?▼

A CORS null origin vulnerability occurs when a server accepts `null` as a valid origin, often exploitable via sandboxed iframes. This misconfiguration allows an attacker to read sensitive API responses that should be restricted.

How do I exploit wildcard origins with credentials during penetration testing?▼

You exploit wildcard origins with credentials by testing if the server returns `Access-Control-Allow-Origin: *` combined with credentialed requests. This misconfiguration enables unauthorized cross-origin reads of authenticated sensitive API data.

Do I need Burp Suite or OWASP ZAP to test for CORS vulnerabilities?▼

Yes, testing for CORS vulnerabilities requires tools like Burp Suite or OWASP ZAP to intercept and modify requests. You also need an attacker-controlled HTTPS server to demonstrate proof-of-concept sensitive data exfiltration.

Why does a server reflecting the Origin header create a web security vulnerability?▼

Reflecting the Origin header creates a web security vulnerability because it bypasses the Same-Origin Policy. An attacker-controlled site can then make authenticated cross-origin requests and read sensitive API responses from the victim's session.