## Nodemailer: Quadratic (O(n^2)) SMTP client reply parsing lets a malicious server or MITM cause a pre-auth remote denial of service

- 種別: advisory
- 重大度: medium
- 関連技術: nodejs
- 公開日時: 2026-10-27T15:04:33.000Z
- 情報源: GitHub Advisory Database (https://github.com/advisories/GHSA-4g23-2xm8-66gc)
- パーマリンク: https://vulnpulse.app/items/ghsa-ghsa-4g23-2xm8-66gc

影響: npm:nodemailer >= 3.0.0, <= 10.0.9 → 10.0.10
The SMTP client response parser reassembles multiline server replies by appending each continuation line onto a single response-queue entry and re-testing whether that entry is still a partial (continuation) reply on every line. The partial-response test runs str.slice(str.lastIndexOf('\n') + 1) on the growing entry, which forces a full flatten of the entire accumulated string on each line. A malicious or compromised SMTP server (or an on-path attacker on a plaintext or pre-STARTTLS hop) that s…