CVE-2026-92598 (CVSS 6.5)

Description

Nodemailer before 9.1.0 fails to apply UTS-46 normalization when encoding international domain names, causing the domain resolver to compute a different Punycode A-label than standards-compliant parsers. Attackers can craft recipient addresses with invisible characters or compatibility mappings that pass domain allow-list checks but are delivered to attacker-controlled domains via SMTP.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

EPSS — Exploit Prediction

0.0040

Probability of exploitation

0.32%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-436 CWE-436

References

Other References

https://github.com/nodemailer/nodemailer/commit/259c32d https://github.com/nodemailer/nodemailer/commit/b212ac4 https://github.com/nodemailer/nodemailer/security/advisories/GHSA-wmmp-3585-3rmp https://www.vulncheck.com/advisories/nodemailer-before-9.1.0-idn-punycode-domain-allow-list-bypass https://github.com/nodemailer/nodemailer/security/advisories/GHSA-wmmp-3585-3rmp

Frequently Asked Questions

What is CVE-2026-92598? +

Nodemailer before 9.1.0 fails to apply UTS-46 normalization when encoding international domain names, causing the domain resolver to compute a different Punycode A-label than standards-compliant parsers. Attackers can craft recipient addresses with invisible characters or compatibility mappings that pass domain allow-list checks but are delivered to attacker-controlled domains via SMTP. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-92598? +

CVE-2026-92598 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0040, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-92598? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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