Vulnerability · Published Sep 26, 2026 · Assigned by VulnCheck
CVE-2026-100701Nodemailer 5.0.0 through 10.0.1 TLS servername Cache Confusion
Medium 5.9
In plain English
A medium-severity improper certificate validation in nodemailer from nodemailer. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-nodemailer | no fix listed | DEBIAN-CVE-2026-100701 |
| Debian:13 | node-nodemailer | no fix listed | DEBIAN-CVE-2026-100701 |
| Debian:14 | node-nodemailer | 10.0.10+~8.0.1-1 | DEBIAN-CVE-2026-100701 |
| Ubuntu:22.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-100701 |
| Ubuntu:24.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-100701 |
| Ubuntu:26.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-100701 |
| Ubuntu:26.10 | node-nodemailer | no fix listed | UBUNTU-CVE-2026-100701 |
| npm | nodemailer | 10.0.2 | GHSA-6vj9-mwq6-2f5v |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nodemailer | nodemailer | 5.0.0 – before 10.0.2 |
Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
References
- GitHub Security Advisory (GHSA-6vj9-mwq6-2f5v) vendor-advisory
- VulnCheck Advisory: Nodemailer 5.0.0 through 10.0.1 TLS servername Cache Confusion third-party-advisory