What’s Vulnerable › Vulnerabilities

CVE-2026-82854: Nodemailer before 8.0.4 SMTP Command Injection via envelope.size

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-31 · updated 2026-10-29
• Weakness: CWE-93

Description

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.

Affected products

• nodemailer: before 8.0.4 — fixed in 8.0.4

How to fix

Upgrade to a fixed version: nodemailer 8.0.4. Check the vendor advisory for mitigations.

References

• https://github.com/nodemailer/nodemailer/security/advisories/GHSA-c7w3-x93f-qmm8
• https://www.vulncheck.com/advisories/nodemailer-before-8.0.3-smtp-command-injection-via-envelope-size

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