Cross-Origin Resource Sharing (CORS)

The Cross-Origin-Resource-Policy (CORP) is an HTTP response header that is used to control and enforce cross-origin resource sharing (CORS) policies for web resources. It specifies which origins are allowed to access a particular resource and under what conditions.

The primary purpose of the Cross-Origin-Resource-Policy header is to restrict the sharing of resources across different origins (domains, protocols, or ports) in a web page. It helps mitigate the risks associated with cross-origin attacks, such as cross-site scripting (XSS) or cross-site request forgery (CSRF).

By specifying the Cross-Origin-Resource-Policy header, web developers can enforce stricter CORS policies and limit access to resources from only the specified origins. This header is set by the server hosting the resource and provides control over how the resource is shared across different origins.

The header allows the following values:

  1. same-origin: Resources are restricted to the same origin, meaning they can only be accessed by the same origin that originated the resource.
  2. same-site: Resources can be accessed by any page on the same site, regardless of the origin.
  3. cross-origin: Resources are accessible by other origins as specified by the Cross-Origin-Resource-Policy-Allow-Origin header. This value allows explicit control over cross-origin sharing.

The Cross-Origin-Resource-Policy header is an additional security measure that complements the Cross-Origin Resource Sharing (CORS) mechanism provided by the Access-Control-Allow-Origin header. It helps to further control resource sharing and prevent unintended or unauthorized access to sensitive resources from different origins.

It’s important to note that the Cross-Origin-Resource-Policy header is relatively new and may not be supported by all web browsers. Therefore, its usage and effectiveness may depend on the specific browser versions and the compatibility of client-side implementations.