RECAP :-

As promised, I’m back — this time with a technical deep dive. 🧑‍💻
In my previous blog, I shared the story of my first bug bounty, mostly from a theoretical perspective.
In this post, we’ll break down the technical details: how I discovered the vulnerability, the steps I followed, and what the actual bug was.
If you haven’t read the previous post yet, I recommend checking it out first [Click Here].

VULNERABILITY / BUG :-

Client-Side Desync / HTTP Request Smuggling

Client-Side Desync (CSD), a form of HTTP Request Smuggling, occurs when a discrepancy between how a client (such as a browser or a proxy) and a server parses an HTTP request allows an attacker to interfere with how subsequent requests are processed. Traditionally, HTTP Request Smuggling focuses on exploiting differences between two servers (like a frontend and a backend). In CSD, however, the target is the way the client interprets the server’s responses. An attacker crafts a malicious HTTP request that tricks the client into misaligning the boundaries of HTTP messages, leading to consequences like leaking sensitive information, web cache poisoning, or even hijacking authenticated sessions. Since CSD abuses subtle parsing inconsistencies and often involves complex timing…