GHSA-49pc-8936-wvfp Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused

• npm lettermint: < 1.5.1 → fixed in 1.5.1

Impact 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. Patches Yes, the issue has been patched. Users should upgrade to v1.5.1 or later. Workarounds If upgrading immediately is not possible, instantiate a new client for each send: ```js const client = new Lettermint({ apiKey: process.env.LETTERMINT_API_KEY }); await client.email.to('...').subject('...').html('...').send(); ``` This ensures no state is carried over between sends.