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

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…

Read on GitHub Advisory Database

On 10/28/2026, 12:04 AM, GitHub Advisory Database published "Nodemailer: Quadratic backtracking in SMTP AUTH mechanism detection regexes allows pre-auth remote denial of service" (type: Advisory). Severity is "Medium" (medium). Related technologies: JavaScript / Node.js.