Medium, CVSS 4.7npmAmendedPublished
Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused
CVE-2026-27492 · GHSA-49pc-8936-wvfp
- Affected
- npm lettermint < 1.5.1
- Fixed in
- 1.5.1· Vendor fix available
- Issue
- 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: This ensures no state is carried over between sends.
Recommended action: Upgrade to 1.5.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.