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Fencer Vulns
medium 6.5

CVE-2026-110871 json

Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service

published 2026-10-14 25 d ago modified 2026-10-22 17 d ago also GHSA-39m8-27wv-hr27 , EUVD-2026-101754

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

Nodemailer from 3.0.0 before 10.0.10 contains a denial of service vulnerability in MessageParser.parseHeaders that allows users to exhaust CPU through quadratic header unfolding. Attackers can supply large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing.

Patch / fix

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

debian advisories DEBIAN-CVE-2026-110871

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-2026-110871 updated cvss 6.5

nodemailer: nodemailer: Denial of Service via inefficient header parsing

  • 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: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images grafana13.1 13.1.7-0.1.hum1, grafana13.2 13.2.3-0.1.hum1, grafana12.4 12.4.12-0.4.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
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
20 d ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/nodemailer/nodemailer/security/advisories/GHSA-39m8-27wv-hr27 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/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 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm nodemailer
>=3.0.0, <10.0.10
10.0.10

Affected products

  • nodemailer nodemailer

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-407 Inefficient Algorithmic Complexity

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.