Vulnerability in Nodemailer
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.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/nodemailer/nodemailer/security/advisories/GHSA-6vj9-mwq6-2f5v (vendor-advisory)
- www.vulncheck.com/advisories/nodemailer-5.0.0-through-10.0.1-tls-servername-cac… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-100701?
- CVE-2026-100701 is a medium-severity vulnerability in Nodemailer, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2026-09-26.
- How severe is CVE-2026-100701?
- Medium severity. CVSS v3 base score is 5.9 out of 10.