Nodemailer: Process-global DNS cache reuses TLS `servername` across transports, enabling cross-tenant SMTP credential disclosure
Affects nodemailerSource GCVE Database
CVSS 5.9 Medium : upgrade to 10.0.2 when convenient.
Data as of 29 Sep 2026, 04:47 UTC
- Patch
- Available – fixed in 10.0.2
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:NWhat to do
Upgrade nodemailer to 10.0.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| npmnodemailer | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users should avoid using direct SMTPS connections with shared DNS hosts and differing TLS servername values to prevent cross-tenant credential leakage. Applying a fix once available is recommended to prevent credential disclosure.
Description
Nodemailer versions from 5.0.0 up to 10.0.1 have a vulnerability in their process-global DNS cache that causes TLS server name indication (SNI) to be reused incorrectly across SMTP transports. This flaw allows one tenant in a multi-tenant environment to cause another tenant's SMTP transport to use the attacker's TLS server name and certificate, leading to potential SMTP credential disclosure. The issue arises because the DNS cache key is only the host, but the cached value includes the TLS server name, which is overwritten and reused improperly.
References
- github.com/nodemailer/nodemailer/security/advisories/GHSA-6vj9-mwq6-2f5v (opens in a new tab)
- github.com/nodemailer/nodemailer/commit/a6512dbcb3c6e7f2f70d3acccc5752defe3c61fe (opens in a new tab)
- github.com/nodemailer/nodemailer (opens in a new tab)
- github.com/nodemailer/nodemailer/releases/tag/v10.0.2 (opens in a new tab)