Email Injection Template

Executive Summary:

This report addresses a significant security vulnerability known as Email Injection within our application. Email Injection occurs when untrusted data, such as user input, is improperly sanitized and included in email headers, allowing attackers to inject malicious content or control the email's recipient, subject, or body. This report aims to detail the vulnerability, its potential impact on our systems and users, and actionable recommendations for mitigation.

Description of the Vulnerability:

Email Injection vulnerabilities arise when untrusted data, such as form input or URL parameters, is directly included in email headers without proper validation or encoding. Attackers can exploit these vulnerabilities by injecting newline characters, special characters, or email headers into the email content, potentially allowing them to manipulate the recipient, subject, or body of the email. Common examples include injecting additional recipients to perform spam or phishing attacks, spoofing email addresses, or injecting malicious content into the email body.


The impact of Email Injection vulnerabilities can be severe, leading to various security risks including unauthorized access to sensitive information, phishing attacks, or compromise of user accounts. Attackers can exploit these vulnerabilities to manipulate email content, impersonate legitimate users or entities, or perform actions such as distributing malware or stealing sensitive information, potentially leading to financial loss, reputational damage, or legal consequences.


The likelihood of exploitation depends on various factors including the visibility of untrusted data in email headers, the effectiveness of input validation and encoding mechanisms, and the attacker's knowledge and motivation. However, given the prevalence of Email Injection vulnerabilities in web applications and the potential impact on system security and user privacy, the risk associated with this vulnerability is significant if not properly mitigated.

Steps to Reproduce:

  1. Identify functionalities within the application that generate and send email notifications or messages.
  2. Submit malicious input containing newline characters, special characters, or email headers via form fields, URL parameters, or other input mechanisms.
  3. Analyze the email messages generated by the application and observe if the injected content or headers are reflected in the email content.
  4. Determine the impact of successful exploitation, including potential phishing attacks, data leakage, or compromise of user accounts.

Recommendations for Developers:

  1. Use Safe Email Sending Libraries: Utilize safe and reputable email sending libraries or frameworks that automatically handle email encoding and prevent injection attacks.
  2. Sanitize and Validate Email Content: Sanitize and validate user-supplied data before including it in email headers or content to prevent injection of malicious content or headers.


Addressing Email Injection vulnerabilities is critical to protecting against phishing attacks, data leakage, and compromise of user accounts within our application. By using safe email sending libraries and implementing proper input validation and sanitization techniques, we can mitigate the risks associated with Email Injection vulnerabilities and enhance the overall security posture of our systems.