PHP Mastering CORS and Bypassing the Same-Origin Policy Issues

Cross-Origin Resource Sharing (CORS) and the Same-Origin Policy (SOP) are two critical concepts in web security, primarily designed to protect user data and prevent malicious web attacks. Understanding these concepts is essential for developers to build secure web applications and resolve common issues related to resource sharing across different origins.

Same-Origin Policy (SOP)

The Same-Origin Policy is a critical security mechanism implemented by web browsers to restrict how a document or script loaded from one origin can interact with resources from another origin. An origin is defined by the scheme (protocol), host (domain), and port of a URL. According to SOP, a web application can only make requests to the same origin it was loaded from, unless explicitly allowed by the target origin.

This policy prevents potentially malicious websites from accessing sensitive data from another site without permission. For example, if you’re logged into your email, SOP prevents another website you’re visiting from making requests to your email provider and reading your emails.

Cross-Origin Resource Sharing (CORS)

CORS is a mechanism that allows restricted resources on a web page to be requested from a domain…