Vulnerability · Published Oct 14, 2026 · Assigned by VulnCheck
CVE-2026-110869Nodemailer 3.0.0 before 10.0.13 ReDoS via SMTP AUTH Mechanism Detection Regexes
High 7.5
In plain English
A high-severity regular-expression denial of service 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 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Nodemailer 3.0.0 before 10.0.13 has a regular expression denial of service in SMTPConnection._actionEHLO, whose four AUTH mechanism detection regexes contain overlapping whitespace sub-patterns that backtrack quadratically. A malicious or man-in-the-middle SMTP server can reply to EHLO with 250-AUTH, a long whitespace run and a non-matching token, blocking the Node.js event loop for tens of seconds to hours before authentication.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-nodemailer | no fix listed | DEBIAN-CVE-2026-110869 |
| Debian:13 | node-nodemailer | no fix listed | DEBIAN-CVE-2026-110869 |
| Debian:14 | node-nodemailer | 10.0.13+~8.0.2-1 | DEBIAN-CVE-2026-110869 |
| Ubuntu:22.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110869 |
| Ubuntu:24.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110869 |
| Ubuntu:26.04:LTS | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110869 |
| Ubuntu:26.10 | node-nodemailer | no fix listed | UBUNTU-CVE-2026-110869 |
| npm | nodemailer | 10.0.13 | GHSA-4ffr-jq9g-5ffx |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nodemailer | nodemailer | 3.0.0 – before 10.0.13 |
Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- GitHub Security Advisory (GHSA-4ffr-jq9g-5ffx) vendor-advisory
- VulnCheck Advisory: Nodemailer 3.0.0 before 10.0.13 ReDoS via SMTP AUTH Mechanism Detection Regexes third-party-advisory