CVE-2026-27492
Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused
Impact
### 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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | lettermint | < 1.5.1 | 1.5.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Lettermint | Lettermint | before 1.5.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/lettermint/lettermint-node/blob/main/CHANGELOG.md#151-2026-02-20
- https://github.com/lettermint/lettermint-node/commit/24a17acbc2429c5eb30391f9df3dc0ea7aaf4de1
- https://github.com/lettermint/lettermint-node/security/advisories/GHSA-49pc-8936-wvfp
- https://github.com/advisories/GHSA-49pc-8936-wvfp
- https://nvd.nist.gov/vuln/detail/CVE-2026-27492