Nodemailer up to 10.0.1 DNS Cache certificate validation

Summaryinfo

A vulnerability has been found in Nodemailer up to 10.0.1 and classified as problematic. Affected by this vulnerability is an unknown functionality of the component DNS Cache. This manipulation causes certificate validation. This vulnerability is tracked as CVE-2026-100701. The attack is possible to be carried out remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic was found in Nodemailer up to 10.0.1. Affected by this vulnerability is an unknown part of the component DNS Cache. The manipulation with an unknown input leads to a certificate validation vulnerability. The CWE definition for the vulnerability is CWE-295. The product does not validate, or incorrectly validates, a certificate. As an impact it is known to affect integrity. The summary by CVE is:

Nodemailer versions 5.0.0 through 10.0.1 use a process-global DNS cache that is keyed only by the DNS host, while each cache entry also stores the caller-specific TLS servername. When two direct TLS/SMTPS transports (secure: true) resolve the same non-IP host with different tls.servername values, the first transport's servername is returned on the cache hit and overwrites the second transport's explicitly configured value, so Nodemailer sends the wrong SNI value and validates the peer certificate against the wrong identity. In multi-tenant services or SNI-routed SMTP gateways, an attacker who can prime the cache can cause a victim transport to connect to the attacker's TLS virtual host and accept the attacker's certificate even with rejectUnauthorized: true, disclosing the victim's SMTP credentials. Fixed in 10.0.2.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-100701 since 09/26/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1587.003 according to MITRE ATT&CK.

Upgrading to version 10.0.2 eliminates this vulnerability.

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Productinfo

Name

• Nodemailer

Version

• 10.0.0
• 10.0.1

Website

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

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