CVE-2026-100701

MEDIUMCVSS 5.9/10

Last modified

CVE-2026-100701 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. 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.

Description

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.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
nodemailernodemailer>= 5.0.0, < 10.0.2

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-100701?
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.
How severe is CVE-2026-100701?
CVE-2026-100701 has a CVSS score of 5.9/10 (MEDIUM severity).
How do I fix CVE-2026-100701?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST