---
id: CVE-2026-92597
title: >-
  Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email
  addresses: in lib/addressparser, a comment closed immediately before a
  non-break character causes the tokenizer to concatenate the atoms surrounding
  the comme…
summary: >-
  Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email
  addresses: in lib/addressparser, a comment closed immediately before a
  non-break character causes the tokenizer to concatenate the atoms surrounding
  the comme…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N'
cwe:
  - CWE-436
  - CWE-1286
vendor: nodemailer
product: nodemailer
affected:
  - nodemailer >= 6.9.16 < 9.1.0
published: '2026-09-16'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T20:25:55.870'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92597'
references:
  - url: 'https://github.com/nodemailer/nodemailer/commit/902b63e'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/nodemailer/nodemailer/security/advisories/GHSA-cc9r-2j5m-2m83
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nodemailer-before-9.1.0-email-domain-validation-bypass-via-rfc-5322-comment
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92597.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92597'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2537871'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92597'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92597'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00255
epssPercentile: 0.17471
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-17T19:17:07.433374Z'
ingestedAt: '2026-09-16T22:06:50.928Z'
---

## Overview

Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email addresses: in lib/addressparser, a comment closed immediately before a non-break character causes the tokenizer to concatenate the atoms surrounding the comment instead of treating the comment as folding whitespace that terminates the domain. A recipient address such as user@good-corp.com(x)evil.com is therefore read by Nodemailer as the single domain good-corp.comevil.com (registrable domain comevil.com, which an attacker can register) and used for both the SMTP envelope (RCPT TO) and the emitted To:/From: headers, while a conformant RFC 5322 parser terminates the domain at the comment and reads good-corp.com. An application that validates the recipient domain with a strict RFC 5322 parser (without inspecting parse defects) or a naive prefix/substring allow-list and then hands the raw address to Nodemailer can be induced to deliver mail to a domain the attacker controls. Fixed in 9.1.0.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Self-service automation portal 2 · no fix planned: Self-service automation portal 2 · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92597.json)