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Fencer Vulns
medium 5.9

CVE-2026-100701 json

Nodemailer 5.0.0 through 10.0.1 TLS servername Cache Confusion

published 2026-09-26 43 d ago modified 2026-09-30 39 d ago also GHSA-6vj9-mwq6-2f5v , EUVD-2026-87674

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm nodemailer 10.0.2
  • nodemailer nodemailer 10.0.2
  • node-nodemailer Debian 14 10.0.10+~8.0.1-1

debian advisories DEBIAN-CVE-2026-100701

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-100701 updated cvss 5.9

nodemailer: nodemailer: Information disclosure via TLS servername cache confusion

  • Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9 Red Hat Enterprise Linux 10 grafana 12.4.3-2.el10 Red Hat Self-service automation portal 2 ansible-automation-platform/bootc-automation-portal-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat Hardened Images grafana13.1 13.1.6-0.3.hum1, grafana13.2 13.2.1-0.6.hum1, grafana12.4 12.4.10-0.7.hum1
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
43 d ago

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
CNA 4.0 6.0 CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm nodemailer
>=5.0.0, <10.0.2
10.0.2

Affected products

  • nodemailer nodemailer

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.