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CVE-2026-100699

Nodemailer is a Node.js email-sending library

Risk score
44/100
CVSS
5.3 v3.1
Exploit chance (30 days)
0.2%
Published
26 Sep 2026

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What to know

What it is
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 ex…
Affected
See advisory
Fix
Apply the vendor's security update; see the linked advisory.
Exploitation
No known exploitation

Why it is Yellow

  • CVSS 5.3 medium
  • On your watchlist: node.js

References

Original 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.

Last activity 26 Sep 2026. Patch Forecast updates every hour.