CVE-2026-100702 [MEDIUM] – Nodemailer before 10.0.2 fails to properly flatten deeply nested arrays in recipient field

Nodemailer before 10.0.2 fails to properly flatten deeply nested arrays in recipient fields such as to, cc, and bcc, allowing attackers to cause stack exhaustion. Attackers can supply a deeply nested JSON recipient array that triggers recursive Array.toString() conversion, exhausting the call stack and terminating the Node.js process.