Summary
Workarounds
If upgrading immediately is not possible, instantiate a new client for each send:
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.
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.
CVE-2026-27492 has a CVSS score of 4.7 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.5.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Yes, the issue has been patched. Users should upgrade to v1.5.1 or later.
Frequently Asked Questions
- What is CVE-2026-27492? CVE-2026-27492 is a medium-severity security vulnerability in lettermint (npm), affecting versions < 1.5.1. It is fixed in 1.5.1.
- How severe is CVE-2026-27492? CVE-2026-27492 has a CVSS score of 4.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of lettermint are affected by CVE-2026-27492? lettermint (npm) versions < 1.5.1 is affected.
- Is there a fix for CVE-2026-27492? Yes. CVE-2026-27492 is fixed in 1.5.1. Upgrade to this version or later.
- Is CVE-2026-27492 exploitable, and should I be worried? Whether CVE-2026-27492 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-27492 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-27492? Upgrade
lettermintto 1.5.1 or later.