Unlocking the Mystery: Exploring the URN Injection Vulnerability

Unlocking the Mystery: Exploring the URN Injection Vulnerability

Hello Hackers,

Today, we will explore the concept of URN Injection in a simple and understandable way. Join us as we uncover the ins and outs of this vulnerability and learn how it can impact web security.


This bug bounty report highlights a critical vulnerability related to URN (Uniform Resource Name) Injection, which poses a significant risk. Exploiting this vulnerability can lead to unauthorized access to sensitive resources, potentially resulting in data leakage. It is imperative to address this issue promptly and implement mitigation measures to uphold the system’s integrity and protect user information.

What is a URN (Uniform Resource Name)?

A URN (Uniform Resource Name) is a persistent identifier for internet resources that leverages the urn system. Unlike physical location-dependent identifiers, URNs provide an enduring and distinct identification for internet resources, even if their associated location changes or disappears over time.


After thorough testing and analysis, a URN Injection vulnerability was identified within the target system. This vulnerability stems from inadequate validation and sanitization of user-supplied URN parameters.

Malicious actors can exploit this vulnerability to manipulate URN values, potentially gaining unauthorized access to sensitive resources or carrying out malicious actions.

Steps To Reproduce:
  1. Visit the login page of example.com.
  2. Locate the “Username” input field.
  3. Inject a malicious URN value into the “Username” field, bypassing any input validation or sanitization. For example: urn:example: user; SELECT * FROM users WHERE username=’admin’ –
  4. Enter any password in the corresponding “Password” field.
  5. Submit the login form.
  6. Observe the application’s behavior. If the URN Injection vulnerability exists, the injected URN value may be processed without proper validation.
  7. Check for unauthorized access or unintended actions:
    • If the application successfully logs in with the injected URN value, unauthorized access to a user’s account has been achieved.

Exploiting this vulnerability may result in:

  • Unauthorized access to restricted resources or actions that should be limited to authenticated users only.
  • Exposure of sensitive data or user information leads to privacy breaches and potential misuse.
  • Abuse of the system through the injection of malicious URNs could further compromise the application by executing arbitrary code or injecting malware.

To mitigate this vulnerability, it is advised to:

  • Implement robust input validation and sanitization mechanisms for all user-supplied URN parameters. This should involve filtering or encoding special characters and verifying the format and structure of URNs.
  • Apply the principle of least privilege by ensuring the proper implementation of access control mechanisms and restricting user access to only necessary resources.

HackerOne Report submitted to LinkedIn: “https://hackerone.com/reports/1806939”.

That’s all for the day…

Happy Hacking!!

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