# CVE-2026-92597: Nodemailer recipient-domain validation bypass via RFC 5322 comment misparse

Source: https://junglewise.ai/threats/cve-2026-92597-nodemailer-recipient-domain-validation-bypass-via-rfc-5322  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-92597 · Severity: medium · CVSS 6.5 · Published 2026-09-16

Nodemailer is a popular Node.js library for sending emails. A flaw in its email address parser allows an attacker to craft malicious recipient addresses that bypass domain validation checks and cause emails to be delivered to attacker-controlled domains. Organizations relying on Nodemailer to enforce domain allowlists or other recipient validation rules could have their emails misdirected.

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

## Quick answers

**Is CVE-2026-92597 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-92597 being exploited in the wild.

**How severe is CVE-2026-92597?** Medium severity, with a CVSS score of 6.5, published 16 September 2026.

**Which products and versions are affected?** Nodemailer 6.9.16 to 9.0.6.

**Is there a fix for CVE-2026-92597?** A patch was published on 2026-09-01: patched in version 9.1.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-92597 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-92597?** 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.

## Technical details

The vulnerability is an Interpretation Conflict (CWE-436) in Nodemailer's RFC 5322 email-address parser. The parser incorrectly treats RFC 5322 comments (parenthesized text like "(x)") as a concatenation point for surrounding domain atoms, rather than as folding whitespace that terminates the domain. An attacker can craft a recipient address such as "user@good-corp.com(x)evil.com" which a compliant RFC 5322 parser (or allowlist checker) sees as "good-corp.com", but Nodemailer parses and routes to "good-corp.comevil.com" (a registrable attacker-controlled domain). The root cause lies in lib/addressparser/index.js where the tokenizer's "noBreak" flag causes concatenation of tokens across comment boundaries. Exploitation requires a mismatch between the application's domain validation logic and Nodemailer's parsing. The flaw has been verified end-to-end against live SMTP servers. A patch is available in version 9.1.0.

## Affected products

- Nodemailer Nodemailer 6.9.16 to 9.0.6

## Identifiers

- CVE-2026-92597
- GHSA-cc9r-2j5m-2m83

## Timeline

- 2026-09-08: disclosed
- 2026-09-01: patched: patched in version 9.1.0

## References

- [https://github.com/nodemailer/nodemailer/security/advisories/GHSA-cc9r-2j5m-2m83](https://github.com/nodemailer/nodemailer/security/advisories/GHSA-cc9r-2j5m-2m83)
- [https://github.com/nodemailer/nodemailer/pull/1848](https://github.com/nodemailer/nodemailer/pull/1848)

## Related threats

- [Nodemailer address parsing bypass in addressparser](https://junglewise.ai/threats/cve-2026-125755-nodemailer-3-0-0-before-10-4-1-contains-an-address-parsing-flaw)
- [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)