Breaking Boundaries: My Journey from limited Stored XSS to Open Redirect & a Sneaky CSRF Referrer…

بسم الله ❤️, اللهم علِّمنا ما ينفعنا، وانفعنا بما علَّمتَنا، وزدنا علماً

I am Ahmed Nayel aka 0xNayel bug hunter and pentester .

In the wild world of bug bounty hunting, some days you stumble upon gold. This is the story of two separate bugs I found on the same program but in different places.

One started as a seemingly not exploitable stored XSS vulnerability, but with a little creativity, I turned it into a open redirect. The other? A CSRF vulnerability that had a decent defense mechanism — until I found a clever way to bypass .

Grab a coffee, and let’s dive into this double-feature bug bounty adventure!

I was testing an application that allowed users to input a display name. After some fuzzing, I discovered that my input was being reflected on multiple pages without proper sanitization. Sweet! But there was a catch: it only allowed 16 characters. This restriction crushed my hopes of injecting a classic <script> tag.

🧠Payloads I tried to use:

But hey, where there’s a will, there’s a way! I started thinking of minimalistic payloads. After some trial and error, I landed on this beauty 16 chars payload:

This tiny payload did two things:

With this, I had a stored XSS that led to an open redirect, meaning I could trick all users into visiting a malicious site.
The payload is executed everywhere in the target in chats , feed , streams which made huge impact to all users

While the stored XSS gave me one attack vector, my exploration of the application’s blog section revealed another weakness. Users could post comments on blog posts, but the comment submission process lacked robust CSRF (Cross-Site Request Forgery) protection. Instead of using secure CSRF tokens, the application relied solely on checking the Referer header to validate requests.

🧠 The Idea

Relying exclusively on the Referer header is a risky practice and opens the door to exploitation. Here’s how I turned this flaw into a working exploit:

Step-by-Step Exploitation:

And exploit is working as expected :

This CSRF flaw is a stark reminder that relying on outdated security measures — like the Referer header alone — can leave an application wide open to exploitation.

In the ever-evolving world of cybersecurity, even the smallest vulnerabilities can unveil a treasure trove of opportunities for a creative mind. My journey — from crafting a minimalistic stored XSS payload to bypassing CSRF protections with clever domain manipulation — reinforces that every bug is a story waiting to be told.

This experience taught me that constraints often spark innovation, and persistence is the key to uncovering hidden flaws in even the most secure systems. Let this serve as a reminder: in the realm of bug bounty hunting, no vulnerability is too small, and every exploit has the potential to make a significant impact.

Keep your curiosity alive, your skills sharp, and never stop exploring the unknown. And if you have your own exploits to share, join the conversation in the comments below — together, we can build a safer digital world.

Happy hunting, and may your bug bounty rewards be ever in your favor!