Skip to main content
VulnerabilityPublished

Nodemailer: Process-global DNS cache reuses TLS `servername` across transports, enabling cross-tenant SMTP credential disclosure

Affects nodemailerSource GCVE Database

0

CVSS 5.9 Medium : upgrade to 10.0.2 when convenient.

Data as of 29 Sep 2026, 04:47 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

What to do

Upgrade nodemailer to 10.0.2.

Affected software

ProductAffectedFixed in
npmnodemailerAffected
  • >=5.0.0 <10.0.2
Fixed in
  • 10.0.2

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

Community reviews

Loading reviews…