Improper Certificate Validation Affecting nodemailer package, versions >=5.0.0 <10.0.2
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-NODEMAILER-20158382
- published27 Sept 2026
- disclosed26 Sept 2026
- creditUnknown
Introduced: 26 Sep 2026
NewCVE-2026-100701 (opens in a new tab)How to fix?
Upgrade nodemailer to version 10.0.2 or higher.
Overview
nodemailer is an Easy as cake e-mail sending from your Node.js applications
Affected versions of this package are vulnerable to Improper Certificate Validation via the DNS cache in src/shared/index.ts, where the TLS server name (SNI) is stored alongside resolved addresses and keyed only by hostname. When two transports in the same process connect to the same host with different tls.servername values, the second transport inherits the server name cached by the first, sends it as SNI, and verifies the peer certificate against it. This allows an attacker to present a certificate issued for the first transport's server name to the second transport's connection, effectively bypassing certificate validation and enabling a MitM attack that exposes credentials sent to the wrong endpoint.