# CVE-2026-125755: Nodemailer address parsing bypass in addressparser

Source: https://junglewise.ai/threats/cve-2026-125755-nodemailer-3-0-0-before-10-4-1-contains-an-address-parsing-flaw  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-125755 · Severity: medium · CVSS 6.5 · Published 2026-11-10

Nodemailer is a widely-used email library for Node.js applications. A flaw in its address parser allows attackers to craft malicious email addresses that pass domain validation checks but actually deliver messages to attacker-controlled addresses, potentially bypassing security controls and spoofing sender identity.

Technologies: [Nodemailer](https://junglewise.ai/threats/technologies/nodemailer). Vendors: [Nodemailer](https://junglewise.ai/threats/vendors/nodemailer).

## Quick answers

**Is CVE-2026-125755 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125755 being exploited in the wild.

**How severe is CVE-2026-125755?** Medium severity, with a CVSS score of 6.5, published 10 November 2026.

**Which products and versions are affected?** Nodemailer 3.0.0 before 10.4.1.

**Is there a fix for CVE-2026-125755?** Yes: fixed in 10.4.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125755 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-125755?** Check whether you run Nodemailer at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 10.4.1

## Technical details

The addressparser component in Nodemailer incorrectly handles RFC 5322 folding whitespace and comments adjacent to domain name dots, truncating domains at these points instead of treating them as continuation per RFC 5322 section 4.4. Attackers can inject crafted to/cc/bcc/replyTo addresses like "ceo@victim.example .allowed.example" that validators parse as "ceo@victim.example.allowed.example" but Nodemailer delivers to "ceo@victim.example", bypassing recipient domain restrictions.

## Affected products

- Nodemailer Nodemailer 3.0.0 before 10.4.1

## Timeline

- 2026-11-10: disclosed
- 2026-11-10: patched

## References

- [https://github.com/nodemailer/nodemailer/blob/3b5cf1eec32c81f287870c8a1c9c09640062cfd5/src/addressparser/index.ts](https://github.com/nodemailer/nodemailer/blob/3b5cf1eec32c81f287870c8a1c9c09640062cfd5/src/addressparser/index.ts)
- [https://github.com/nodemailer/nodemailer/commit/c2b9c41bb81b2294ebadd294ad15ff035a17d0a5](https://github.com/nodemailer/nodemailer/commit/c2b9c41bb81b2294ebadd294ad15ff035a17d0a5)

## Related threats

- [Nodemailer address parsing bypass in nested RFC 5322 comments](https://junglewise.ai/threats/cve-2026-121424-nodemailer-from-3-0-0-before-10-1-4-contains-an-address-parsing)
- [Nodemailer addressparser RFC 5322 comment parsing bypass](https://junglewise.ai/threats/nodemailer-a-nested-comment-ends-early-in-addressparser-releasing-the-4e80613c)
- [Nodemailer addressparser group terminator bypass in quoted strings](https://junglewise.ai/threats/nodemailer-a-inside-a-quoted-string-or-comment-ends-an-address-group-b8b045f9)
- [Nodemailer addressparser angle-addr parsing bypass](https://junglewise.ai/threats/nodemailer-a-inside-a-quoted-local-part-ends-an-angle-addr-early-in-28663cfb)
- [Nodemailer quadratic DKIM header unfolding denial of service](https://junglewise.ai/threats/duplicate-advisory-nodemailer-quadratic-o-n-2-dkim-header-unfolding-a2b86ca5)