Credential Stuffing

Executive Summary:

This report addresses a significant security vulnerability known as Credential Stuffing within our application. Credential Stuffing occurs when attackers use previously compromised credentials, obtained from data breaches or leaks, to gain unauthorized access to user accounts on other platforms or services due to password reuse. This report aims to detail the vulnerability, its potential impact on our systems and users, and actionable recommendations for mitigation.

Description of the Vulnerability:

Credential Stuffing exploits the practice of users reusing the same username and password combinations across multiple online platforms or services. Attackers leverage previously compromised credentials, often obtained from data breaches or leaks, and systematically attempt to authenticate against other platforms or services using the same credentials. Automated tools are commonly used to conduct large-scale credential stuffing attacks against authentication interfaces, such as login pages or APIs, in search of valid credentials.


The impact of Credential Stuffing attacks can be severe, leading to unauthorized access to user accounts, data breaches, or compromise of sensitive information. By exploiting password reuse, attackers can gain access to privileged accounts, steal personal data, or perform fraudulent activities on behalf of compromised users, potentially leading to financial loss, reputational damage, or legal consequences.


The likelihood of exploitation depends on various factors including the prevalence of password reuse among users, the visibility of authentication interfaces, and the effectiveness of password policies and detection mechanisms. However, given the widespread use of reused passwords and the availability of automated tools for conducting credential stuffing attacks, the risk associated with this vulnerability is significant if not properly mitigated.

Steps to Reproduce:

  1. Obtain a list of previously compromised credentials from data breaches or leaks.
  2. Identify authentication interfaces, such as login pages or APIs, that accept username-password combinations.
  3. Use automated tools to systematically try previously compromised credentials against these authentication interfaces.
  4. Analyze the authentication responses and identify successful login attempts indicating reused credentials.

Recommendations for Developers:

  1. Educate Users about Password Hygiene: Educate users about the risks of password reuse and encourage them to use unique passwords for each online platform or service.
  2. Implement Multi-Factor Authentication (MFA): Implement multi-factor authentication (MFA) to add an additional layer of security beyond passwords, mitigating the risk of unauthorized access even if passwords are compromised.


Addressing Credential Stuffing vulnerabilities is critical to protecting against unauthorized access and data breaches within our application. By educating users about password hygiene and implementing multi-factor authentication (MFA), we can mitigate the risks associated with Credential Stuffing attacks and enhance the overall security posture of our systems.