---
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
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
tags:
  - nvd
ingestedAt: '2026-10-15T00:02:07.189Z'
---

## 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.