[ CVE-2026-110871 · Published 14 Oct 2026 ]
Nodemailer: Quadratic (O(n^2)) DKIM header unfolding lets a large folded header cause remote denial of service during signing
CVSS 6.5
EPSS <1%Fix available
[ Why it matters ]Priority signals
- Public proof-of-concept exploit exists (CISA SSVC)
[ Description ]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.
[ Fixes ]Fixes and patches
- nodemailer 10.0.10Fixed version · GitHub Advisories · npm package nodemailer: upgrade to 10.0.10 or later (affected >= 3.0.0, <= 10.0.9)
[ Packages ]Affected open-source packages
- nodemailer npmAffected >= 3.0.0, <= 10.0.9 · fixed in 10.0.10 · GHSA-39m8-27wv-hr27