Critical Command Injection Vulnerability in Nodemailer Package

Background

Nodemailer is a popular Node.js module used for sending emails. It simplifies the process of email creation and delivery, supporting various transport methods, including SMTP and sendmail. The package is widely utilized in web applications for sending notifications, alerts, and user communications. However, a vulnerability has been identified in versions prior to 6.4.16, which could allow attackers to exploit crafted recipient email addresses.

Vulnerability Detail

The vulnerability, identified as CVE-2020-7769, arises from the improper handling of recipient email addresses in the sendmail transport method of Nodemailer. Attackers can inject arbitrary command flags through specially crafted email addresses, potentially leading to unauthorized command execution on the server. This could result in data breaches, service disruptions, or unauthorized access to sensitive information. The vulnerability has a CVSS score of 9.8, indicating its critical severity.

sudo apt-get install --only-upgrade node-nodemailer

Workaround

If upgrading is not immediately feasible, a temporary workaround is to validate and sanitize recipient email addresses before passing them to the Nodemailer sendmail transport. This can help mitigate the risk of command injection. Example code for validation:

const validateEmail = (email) => {
  const regex = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
  return regex.test(email);
};

if (validateEmail(recipientEmail)) {
  // Proceed with sending email
} else {
  // Handle invalid email address
}

Conclusion

The CVE-2020-7769 vulnerability in the Nodemailer package poses a significant risk due to its potential for command injection through email addresses. It is crucial for users to upgrade to version 6.4.16 or later to secure their applications. In the interim, validating email addresses can help mitigate risks.

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