CRLF injection in nodemailer - #VU125299
Published: April 8, 2026
Vulnerability identifier: #VU125299
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: N/A
CWE-ID: CWE-93
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: nodemailer
Affected software:
nodemailer
nodemailer
Detailed vulnerability description
The vulnerability allows a remote user to inject arbitrary SMTP commands.
The vulnerability exists due to improper neutralization of CRLF sequences in lib/smtp-connection/index.js when processing a custom envelope.size value in sendMail(). A remote user can supply a crafted envelope.size value containing CRLF characters to inject arbitrary SMTP commands.
This issue can silently add attacker-controlled recipients to outgoing emails. Exploitation requires the application to explicitly pass a custom envelope object with a size property to sendMail().
Remediation
Install security update from vendor's website.