## Nodemailer: Quadratic backtracking in SMTP AUTH mechanism detection regexes allows pre-auth remote denial of service

- 種別: advisory
- 重大度: medium
- 関連技術: nodejs
- 公開日時: 2026-10-27T15:04:39.000Z
- 情報源: GitHub Advisory Database (https://github.com/advisories/GHSA-4ffr-jq9g-5ffx)
- パーマリンク: https://vulnpulse.app/items/ghsa-ghsa-4ffr-jq9g-5ffx

影響: npm:nodemailer >= 3.0.0, <= 10.0.12 → 10.0.13
Nodemailer's SMTP client applies four regular expressions to a peer's EHLO response to detect the supported SASL mechanisms. Each pattern uses an alternation with two overlapping whitespace-matching sub-patterns, which produces quadratic (O(n^2)) backtracking whenever the mechanism name is absent from the line. A malicious or MITM SMTP server that answers EHLO with 250-AUTH followed by a long whitespace-only run and a non-matching token blocks the Node.js event loop for tens of seconds to hours…