Securing Web Resources with Cross-Origin Resource Policy (CORP)

As the internet continues to evolve, web security becomes increasingly important. Cross-origin resource requests, where a web page requests resources (such as images, scripts, or stylesheets) from different domains, can pose security risks if not handled correctly. This is where Cross-Origin Resource Policy (CORP) steps in, providing web developers and site owners with the tools to secure their web resources. In this blog post, we’ll explore what CORP is, why it’s crucial, and how it helps enhance web security.

What is Cross-Origin Resource Policy (CORP)?

Cross-Origin Resource Policy (CORP) is a security feature that allows web developers and website owners to specify how their web resources can be fetched and used by other websites. It aims to control cross-origin resource requests and mitigate the risks associated with loading resources from different origins.

Why is CORP Important?

  1. Mitigating Security Risks: CORP is vital for mitigating various security risks, including Cross-Site Scripting (XSS) and Cross-Site Request Forgery (CSRF). By enforcing CORP policies, developers can reduce the chances of malicious code execution and unauthorized cross-origin resource access.
  2. Enhancing Privacy Protection: CORP helps protect user privacy by ensuring that sensitive resources, such as cookies or session data, are not accessible to third-party websites. This prevents data leakage and enhances user privacy.
  3. Preventing Data Exfiltration: CORP can prevent data exfiltration by controlling how resources are loaded and restricting which websites can access them. This is particularly important for valuable or confidential data.

How Does CORP Work?

CORP is implemented using HTTP headers that are sent by the web server along with the resource response. These headers inform the browser about the resource’s CORP policy, ensuring that it is used only in the specified manner. Key components of CORP include:

  1. Cross-Origin-Resource-Policy (CORP) Header: This header defines the policy for a specific resource. It can have values like ‘same-origin’, ‘same-site’, or ‘cross-origin’, each with varying levels of permissiveness regarding cross-origin access.
  2. Cross-Origin-Opener-Policy (COOP) and Cross-Origin-Embedder-Policy (COEP): CORP often works in conjunction with the Cross-Origin-Opener-Policy (COOP) and Cross-Origin-Embedder-Policy (COEP) headers. COOP specifies how a web page’s browsing context interacts with other pages, while COEP controls how resources from different origins are embedded within a page.


Cross-Origin Resource Policy (CORP) is a powerful tool in the web developer’s arsenal for securing web resources and enhancing web security and privacy. As web threats continue to evolve, CORP remains a crucial feature for protecting against cross-origin vulnerabilities and data breaches.

Web developers and website owners should be aware of CORP and implement it effectively to safeguard their web resources and users’ online experiences. By incorporating CORP headers into their applications, developers can significantly enhance the security and privacy of their web resources, contributing to a safer and more secure online environment for all.

Jacob Billings
PhD Candidate - Complex Systems

I am a software engineer, linguist, and researcher of Complex Systems. I hold a bachelor's degree in Middle Eastern Studies from the University of Utah, a Master’s degree in linguistics from Francisco Marroquín University in Guatemala City, and I am a doctoral candidate in Complex Systems at the Polytechnic University in Madrid, Spain.

Software Development: I bring over 20 years of experience in developing software for multiple clients in various environments. I have a solid knowledge of PHP, Javascript, MySQL, NoSQL, Python, and Java.

Over my career, I have had the opportunity to work on projects for some of the most recognized brands on the planet. Brands like Marriott Hotels, Microsoft, Ashland Chemical, Capital One Credit Cards, Cadbury Schweppes, GE and more. This has given me an in-depth understanding of my client's challenges as they grow. I know how to get a company from startup to maturity with technology. My specialties are in E-commerce(specifically Magento), process automation, and security.