---
id: CVE-2026-110871
title: >-
  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
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…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-1322
  - CWE-407
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T23:17:28.953'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110871'
references:
  - url: >-
      https://github.com/nodemailer/nodemailer/security/advisories/GHSA-39m8-27wv-hr27
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.0.10-quadratic-dkim-header-unfolding-denial-of-service
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-110871.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-110871'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2552965'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-110871'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110871'
  - url: >-
      https://github.com/nodemailer/nodemailer/commit/28a5909cec27646cb001dc7e97a8f5d26c973078
  - url: 'https://github.com/nodemailer/nodemailer/releases/tag/v10.0.10'
  - url: 'https://github.com/advisories/GHSA-39m8-27wv-hr27'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - exploit-available
  - ghsa
  - npm
ingestedAt: '2026-10-15T00:02:07.189Z'
vendor: nodemailer
product: nodemailer
affected:
  - nodemailer >= 3.0.0 < 10.0.10
epss: 0.00381
epssPercentile: 0.31879
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-20T02:27:46.223988Z'
aliases:
  - GHSA-39m8-27wv-hr27
ecosystem: npm
patched:
  - nodemailer 10.0.10
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Self-service automation portal 2 · no fix planned: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Self-service automation portal 2 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-110871.json)

## Package advisory (CVE-2026-110871)

Affected packages:

- `nodemailer >= 3.0.0, <= 10.0.9`

Patched in:

- `nodemailer 10.0.10`

Source: https://github.com/advisories/GHSA-39m8-27wv-hr27