Advisories for Npm/Lettermint package

2026

Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused

Email properties (such as to, subject, html, text, and attachments) are not reset between sends when a single client instance is reused across multiple .send() calls. This can cause properties from a previous send to leak into a subsequent one, potentially delivering content or recipient addresses to unintended parties. Applications sending emails to different recipients in sequence — such as transactional flows like password resets or notifications — are affected.