File path traversal,traversal-sequences stripped with superfluous URL-decode

Platform: PortSwigger | Category: Directory-traversal | Type: Lab | Difficulty: N/A | OS: N/A | Author: XESXOR | Date: 2026-08-24 | Status: Solved Techniques: Web Security Academy, Directory-traversal

Summary

Walkthrough of the PortSwigger Web Security Academy lab File path traversal,traversal-sequences stripped with superfluous URL-decode (Directory-traversal). This lab demonstrates a directory-traversal vulnerability and its exploitation to achieve the lab objectives.

Lab Overview

PortSwigger Web Security Academy — Directory-traversal

This writeup is part of the XESXOR PortSwigger collection. The original lab description and solution have been preserved and reformatted for clarity.

Lab Description :

Solution :

The request which loads images loooks like ,

In this lab , the server strips all the directory traversal sequences ../ & also ..%2F..%2F..%2F(doule encoding), so to bypass this we can use triple encoding.

So to bypass this we use triple encoded version of ../../../etc/passwd as ..%252F..%252F..%252Fetc%252Fpasswd as payload.

Now we got the response back containing the response of the file.

Key Takeaways / Lessons

• Understanding Directory-traversal detection and exploitation is crucial for web security.
• Always validate and sanitize user input; implement proper access controls.
• This lab is part of the PortSwigger Web Security Academy — practice in a safe, legal environment.

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Crafted by XESXOR Research • 2026-08-24 • PortSwigger Web Security Academy • Lab: File path traversal,traversal-sequences stripped with superfluous URL-decode