Nodemailer up to 8.0.3 Envelope Size sendMail envelope.size command injection

Summaryinfo

A vulnerability, which was classified as critical, has been found in Nodemailer up to 8.0.3. Affected by this vulnerability is the function sendMail of the component Envelope Size. The manipulation of the argument envelope.size leads to command injection. This vulnerability is referenced as CVE-2026-82854. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Nodemailer up to 8.0.3 and classified as critical. This issue affects the function sendMail of the component Envelope Size. The manipulation of the argument envelope.size with an unknown input leads to a command injection vulnerability. Using CWE to declare the problem leads to CWE-77. The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Nodemailer before 8.0.4 is vulnerable to SMTP command injection through the unsanitized envelope.size parameter. When an application passes a custom envelope object with a size property containing CRLF characters to sendMail(), the value is concatenated into the SMTP MAIL FROM command (as SIZE=...) without sanitization, allowing injection of arbitrary SMTP commands such as RCPT TO to silently add attacker-controlled recipients. Exploitation requires the application to expose the envelope size to attacker-controlled input, as Nodemailer does not include size in the default auto-constructed envelope.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-82854 since 08/31/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1202 for this issue.

Upgrading to version 8.0.4 eliminates this vulnerability.

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Productinfo

Name

• Nodemailer

Version

• 8.0.0
• 8.0.1
• 8.0.2
• 8.0.3

Website

• Product: https://github.com/nodemailer/nodemailer/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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