Vulnerability · Published Feb 21, 2026 · Assigned by GitHub_M

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

Medium 4.7

In plain English

A medium-severity security flaw in lettermint-node from lettermint. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.7Medium

Exploit odds (30 days)0.2%top 91.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	lettermint	1.5.1	GHSA-49pc-8936-wvfp

Affected products (as reported)

Vendor	Product	Versions
lettermint	lettermint-node	< 1.5.1

Weakness: CWE-488 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

References

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