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OpenAdvisories
Medium · 5.3 CVE-2026-100699 EUVD-2026-87672GHSA-fcjc-3m4q-q926GHSA-g57g-f23g-4646

Nodemailer before 10.0.9 Malformed Envelope Recipient via RFC 5322 Comment

Published Sep 26, 2026 · Updated Sep 28, 2026 · Assigned by VulnCheck

Description

Nodemailer is a Node.js email-sending library. In versions >= 9.1.0 and < 10.0.9, the address parser (src/addressparser) mishandles addresses whose local-part is a quoted string and that are followed by RFC 5322 comments, allowing trailing comment-separated domain atoms to be retained in the normalized address. For example, the input "user"@example.com(x)evil.com is parsed to the address value 'user@example.com evil.com', which contains additional attacker-controlled domain text separated by a literal space. This parsed value is used without further strict recipient validation when the message envelope is built (envelope.to in src/mime-node), so a malformed/ambiguous recipient address can be accepted and placed in the SMTP envelope. Whether this results in delivery to an unintended recipient on real SMTP servers has not been confirmed. The issue is a variant of the RFC 5322 comment parsing problem addressed in GHSA-cc9r-2j5m-2m83, affecting the separate quoted-local-part code path. Version 10.0.9 contains a fix.

Affected products

VendorProductAffectedFixed
nodemailer nodemailer 9.1.0 – < 10.0.9 10.0.9

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 node-nodemailer 10.0.10+~8.0.1-1 —
Debian 13 node-nodemailer No fix yet —
Debian 12 node-nodemailer No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 node-nodemailer No fix yet —
Ubuntu 26.04 LTS node-nodemailer No fix yet —
Ubuntu 24.04 LTS node-nodemailer No fix yet —
Ubuntu 22.04 LTS node-nodemailer No fix yet —
Ubuntu 20.04 LTS node-nodemailer No fix yet —

Affected packages

EcosystemPackageAffectedFixedRecord
npm nodemailer >= 9.1.0, < 10.0.9 10.0.9 GHSA-g57g-f23g-4646

Advisories 1

References