Vulnerability · Published Oct 14, 2026 · Assigned by VulnCheck
CVE-2026-110871Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service
Medium 6.5
In plain English
A medium-severity uncontrolled resource consumption in nodemailer from nodemailer. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-nodemailer | no fix listed | DEBIAN-CVE-2026-110871 |
| Debian:13 | node-nodemailer | no fix listed | DEBIAN-CVE-2026-110871 |
| Debian:14 | node-nodemailer | 10.0.10+~8.0.1-1 | DEBIAN-CVE-2026-110871 |
| Ubuntu:22.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110871 |
| Ubuntu:24.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110871 |
| Ubuntu:26.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110871 |
| Ubuntu:26.10 | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110871 |
| npm | nodemailer | 10.0.10 | GHSA-39m8-27wv-hr27 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nodemailer | nodemailer | 3.0.0 – before 10.0.10 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
References
- GitHub Security Advisory (GHSA-39m8-27wv-hr27) vendor-advisory
- VulnCheck Advisory: Nodemailer 3.0.0 before 10.0.10 Quadratic DKIM Header Unfolding Denial of Service third-party-advisory