CVE-2020-7769
Command Injection vulnerability in nodemailer

What is CVE-2020-7769 About?

The 'nodemailer' package before version 6.4.16 is vulnerable to arbitrary command flag injection in its sendmail transport. This flaw allows an attacker to inject malicious command flags via crafted recipient email addresses. This is a moderately complex vulnerability to exploit, requiring specific crafting of email addresses.

Affected Software

Technical Details

This vulnerability occurs in the sendmail transport mechanism of the 'nodemailer' package. When the package processes recipient email addresses, it fails to properly sanitize or escape these addresses before passing them as arguments to the underlying 'sendmail' command. An attacker can craft a special recipient email address that includes command line flags or parameters for the 'sendmail' utility. When 'nodemailer' invokes 'sendmail' with this crafted address, the injected flags are interpreted by 'sendmail', allowing the attacker to alter its behavior or even execute arbitrary commands. The specific attack vector relies on the attacker controlling the 'to', 'cc', or 'bcc' fields of an email sent through the vulnerable 'nodemailer' application.

What is the Impact of CVE-2020-7769?

Successful exploitation may allow attackers to execute arbitrary commands on the underlying system, leading to remote code execution, data exfiltration, or system compromise.

What is the Exploitability of CVE-2020-7769?

Exploitation requires the attacker to submit a crafted email address through an application using the vulnerable 'nodemailer' package configured with a sendmail transport. The complexity lies in understanding the 'sendmail' utility's command-line parsing and crafting the appropriate injection string. Authentication might be required to send emails, depending on the application's design, but the vulnerability is in the backend processing. No specific elevated privileges are needed on the system running 'nodemailer' for the injection itself, as the vulnerability affects the privileges of the 'sendmail' process. This is typically a remote exploit where the attacker interacts with a web application's email functionality. The likelihood of exploitation increases if an application directly exposes email sending features to untrusted users or processes external input for recipient addresses without proper validation.

What are the Known Public Exploits?

What are the Available Fixes for CVE-2020-7769?

Available Upgrade Options

• nodemailer
  • <6.4.16 → Upgrade to 6.4.16

Additional Resources

• https://github.com/nodemailer/nodemailer/commit/ba31c64c910d884579875c52d57ac45acc47aa54
• https://nvd.nist.gov/vuln/detail/CVE-2020-7769
• https://github.com/nodemailer/nodemailer/blob/33b62e2ea6bc9215c99a9bb4bfba94e2fb27ebd0/lib/sendmail-transport/index.js#L75
• https://github.com/nodemailer/nodemailer/blob/33b62e2ea6bc9215c99a9bb4bfba94e2fb27ebd0/lib/sendmail-transport/index.js%23L75
• https://github.com/nodemailer/nodemailer/commit/ba31c64c910d884579875c52d57ac45acc47aa54
• https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1039742
• https://osv.dev/vulnerability/GHSA-48ww-j4fc-435p
• https://www.npmjs.com/package/nodemailer
• https://github.com/nodemailer/nodemailer/blob/33b62e2ea6bc9215c99a9bb4bfba94e2fb27ebd0/lib/sendmail-transport/index.js%23L75
• https://snyk.io/vuln/SNYK-JS-NODEMAILER-1038834

What are Similar Vulnerabilities to CVE-2020-7769?

Similar Vulnerabilities: CVE-2018-1000632 , CVE-2018-1000216 , CVE-2017-1000499 , CVE-2014-3707 , CVE-2011-3561