Inefficient Algorithmic Complexity Affecting nodemailer package, versions >=9.1.0 <10.0.5
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-19784395
- published14 Sept 2026
- disclosed13 Sept 2026
- creditMario Madersbacher
Introduced: 13 Sep 2026
NewCVE-2026-90776 (opens in a new tab)How to fix?
Upgrade nodemailer to version 10.0.5 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 Inefficient Algorithmic Complexity in its address parser (src/addressparser/index.ts), whose join condition evaluates parts[parts.length - 1].slice(-1) before the cheaper token.value.charAt(0) check, flattening the accumulator on every token and making the parse quadratic in the length of the address value. An attacker can block the Node.js event loop for roughly 7 seconds per message, stalling all other work on it, by supplying an address value of about 640 KB whose atoms are separated by RFC 5322 comments, such as a@b(c)@b(c)@b(c).... This requires the application to parse untrusted addresses, which is reachable through mailparser wherever inbound email headers are processed.