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As a bug bounty hunter, I often explore different features of web applications, especially the login and redirection mechanisms. These parts are very common places for security mistakes, especially if developers forget to validate user inputs properly.

Recently, while testing one of the domains I had permission to test (target.com), I found a simple but potentially dangerous Open Redirect vulnerability. This kind of issue may seem small at first, but in the wrong hands, it can be used to trick users, launch phishing attacks, and even sometimes help with more serious attacks like SSRF.

Let me explain how I found it and how it works.

Before we dive into the vulnerability, let’s take a moment to understand what Open Redirect means.

An Open Redirect happens when a website lets you redirect users to any URL you provide in a link, without checking if the destination is safe or trusted. For example, if you click on a link like:

https://target.com/login?redirect_url=https://evil.com

And after logging in, the website sends you directly to https://evil.com, that’s an Open Redirect. A secure website should never allow this unless the…