All vulnerabilities
CVE-2026-100699GHSA-g57g-f23g-4646

Nodemailer before 10.0.9 Malformed Envelope Recipient via RFC 5322 Comment

nodemailer nodemailernpmLibraries & packages
CVSS
6.9Medium
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 28 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.19%Chance of exploitation activity in the next 30 days, higher than 8% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in10.0.9Fixed versionCVE List
Published26 Sep 2026Updated 30 Sep 2026CVE List

What fixes it

  • 10.0.9nodemailerCVE List
  • 10.0.9nodemailer, npmOSVnpm install nodemailer@10.0.9

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 3

  • nodemaileraffected: 9.1.0 before 10.0.9CVE List
  • nodemailerunaffected: 10.0.9CVE List
  • nodemailer, npmfrom 9.1.0, fixed in 10.0.9OSV

References 2