Web Application Security, A Beginner's Guide

Exceptions to the Same-Origin Policy

However, even here in the real world, there are ways for applications to make exceptions to the same-origin policy. The demand from web application developers for the ability to create full-featured mashups like Amy’s Flowers—but significantly more secure—is just too great to ignore, so browser manufacturers and browser plugin manufacturers have given them the ability to bypass the same-origin policy in certain controlled ways. But if you accidentally misuse these bypasses, you can leave your application open to attack and leave your users at risk of losing their private data. Let’s look at a few ways to get around the same-origin policy, and a few ways to ensure this is done as securely as possible.

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