Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email addresses: in lib/addressparser, a comment closed immediately before a non-break character causes the tokenizer to concatenate the atoms surrounding the comment instead of treating the comment as folding whitespace that terminates the domain. A recipient address such as user@good-corp.com(x)evil.com is therefore read by Nodemailer as the single domain good-corp.comevil.com (registrable domain comevil.com, which an attacker can register) and used for both the SMTP envelope (RCPT TO) and the emitted To:/From: headers, while a conformant RFC 5322 parser terminates the domain at the comment and reads good-corp.com. An application that validates the recipient domain with a strict RFC 5322 parser (without inspecting parse defects) or a naive prefix/substring allow-list and then hands the raw address to Nodemailer can be induced to deliver mail to a domain the attacker controls. Fixed in 9.1.0.
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Fixes
Solution
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Workaround
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References
History
Wed, 16 Sep 2026 22:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Nodemailer versions >= 6.9.16 and < 9.1.0 mis-parse RFC 5322 comments in email addresses: in lib/addressparser, a comment closed immediately before a non-break character causes the tokenizer to concatenate the atoms surrounding the comment instead of treating the comment as folding whitespace that terminates the domain. A recipient address such as user@good-corp.com(x)evil.com is therefore read by Nodemailer as the single domain good-corp.comevil.com (registrable domain comevil.com, which an attacker can register) and used for both the SMTP envelope (RCPT TO) and the emitted To:/From: headers, while a conformant RFC 5322 parser terminates the domain at the comment and reads good-corp.com. An application that validates the recipient domain with a strict RFC 5322 parser (without inspecting parse defects) or a naive prefix/substring allow-list and then hands the raw address to Nodemailer can be induced to deliver mail to a domain the attacker controls. Fixed in 9.1.0. | |
| Title | Nodemailer before 9.1.0 Email Domain Validation Bypass via RFC 5322 Comment | |
| First Time appeared |
Nodemailer
Nodemailer nodemailer |
|
| Weaknesses | CWE-436 | |
| CPEs | cpe:2.3:a:nodemailer:nodemailer:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Nodemailer
Nodemailer nodemailer |
|
| References |
| |
| Metrics |
cvssV3_1
|
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MITRE
Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-09-16T21:47:01.599Z
Reserved: 2026-09-16T13:48:49.970Z
Link: CVE-2026-92597
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-16T22:18:30.700
Modified: 2026-09-16T22:18:30.700
Link: CVE-2026-92597
Redhat
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OpenCVE Enrichment
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Weaknesses