Vulnerabilities in pkg:npm/lettermint

PACKAGE
Advisory Identifier: GHSA-49pc-8936-wvfp
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Advisory Summary

CVE-2026-27492 is a MODERATE (CVSS 4.7) lettermint node.js sdk leaks email vulnerability (CWE-488: Exposure of Data Element to Wrong Session) affecting Lettermint libraries in the npm ecosystem. The issue involves lettermint node.js sdk leaks email properties to unintended recipients when client instance is reused. Remediation is available by upgrading affected packages to version 1.5.1.

1 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/lettermint

1 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/lettermint. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-49pc-8936-wvfp CVE-2026-27492 MODERATE Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused

CVE-2026-27492 at a Glance

CVE Identifier CVE-2026-27492
GHSA Identifier GHSA-49pc-8936-wvfp
Severity MODERATE
CVSS v3.1 Base Score 4.7
CWE Classification CWE-488: Exposure of Data Element to Wrong Session
Affected Product Lettermint
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 4.7

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Local (AV:L)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-27492

To remediate this vulnerability, upgrade all affected Lettermint dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

lettermint fixed: 1.5.1 
npm install lettermint@1.5.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls lettermint

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27492, inspect your project dependencies using npm:

npm ls lettermint

Analyze the terminal output to locate any version of Lettermint in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.1), your application is affected.

Note: The npm ls lettermint command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-488: Exposure of Data Element to Wrong Session, where the product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session. In Lettermint, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-27492 Affected Lettermint Versions

1 component(s)
Fixed Versions:
1.5.1
Product / Package Ecosystem Affected Versions Fixed Version
lettermint
npm/lettermint
npm
< 1.5.1
1.5.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/lettermint/lettermint-node/security/advisories/GHSA-49pc-8936-wvfp
NVD — CVE-2026-27492 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27492
Security Fix Commit FIX COMMIT
https://github.com/lettermint/lettermint-node/commit/24a17acbc2429c5eb30391f9df3dc0ea7aaf4de1
Lettermint Source Repository REPOSITORY
https://github.com/lettermint/lettermint-node
Lettermint Source Repository REPOSITORY
https://github.com/lettermint/lettermint-node/blob/main/CHANGELOG.md#151-2026-02-20

Frequently Asked Questions

What is CVE-2026-27492?
CVE-2026-27492 is a security vulnerability in Lettermint involving Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused under CWE-488: Exposure of Data Element to Wrong Session.
Which Lettermint versions are affected?
Affected versions include releases prior to 1.5.1 across affected packages: lettermint.
What version fixes CVE-2026-27492?
Upgrading to 1.5.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is lettermint affected?
Yes, lettermint is affected in releases prior to 1.5.1. Upgrade your dependency to 1.5.1 or later.
What is the CVSS score of CVE-2026-27492?
CVE-2026-27492 has a CVSS v3.1 base score of 4.7 (MODERATE) with vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-27492?
CVE-2026-27492 is classified under CWE-488: Exposure of Data Element to Wrong Session (The product does not sufficiently enforce boundaries between the states of different sessions, causing data to be provided to, or used by, the wrong session.).
How can I check npm dependencies for CVE-2026-27492?
Run the dependency tree command: 'npm ls lettermint'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-49pc-8936-wvfp",
  "modified" : "2026-02-23T22:30:18Z",
  "published" : "2026-02-20T21:14:49Z",
  "aliases" : [ "CVE-2026-27492" ],
  "summary" : "Lettermint Node.js SDK leaks email properties to unintended recipients when client instance is reused",
  "details" : "### Impact\nEmail 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.\n\n### Patches\nYes, the issue has been patched. Users should upgrade to v1.5.1 or later.\n\n### Workarounds\nIf upgrading immediately is not possible, instantiate a new client for each send:\n```js\nconst client = new Lettermint({ apiKey: process.env.LETTERMINT_API_KEY });\nawait client.email.to('...').subject('...').html('...').send();\n```\n\nThis ensures no state is carried over between sends.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "lettermint"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.5.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/lettermint/lettermint-node/security/advisories/GHSA-49pc-8936-wvfp"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27492"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lettermint/lettermint-node/commit/24a17acbc2429c5eb30391f9df3dc0ea7aaf4de1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/lettermint/lettermint-node"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lettermint/lettermint-node/blob/main/CHANGELOG.md#151-2026-02-20"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-488" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-20T21:14:49Z",
    "nvd_published_at" : "2026-02-21T11:15:57Z"
  }
}