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

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…

Read on GitHub Advisory Database

On 10/28/2026, 12:04 AM, GitHub Advisory Database published "Nodemailer: Quadratic (O(n^2)) SMTP client reply parsing lets a malicious server or MITM cause a pre-auth remote denial of service" (type: Advisory). Severity is "Medium" (medium). Related technologies: JavaScript / Node.js.