CVE-2026-21483: Nadh Listmonk

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

listmonk is a standalone, self-hosted, newsletter and mailing list manager. Prior to version 6.0.0, lower-privileged user with campaign management permissions can inject malicious JavaScript into campaigns or templates. When a higher-privileged user (Super Admin) views or previews this content, the XSS executes in their browser context, allowing the attacker to perform privileged actions such as creating backdoor admin accounts. The attack can be weaponized via the public archive feature, where victims simply need to visit a link - no preview click required. Version 6.0.0 fixes the issue.

Affected products

• Nadh Listmonk: before 6.0.0 (fixed in 6.0.0)

Published 2026-01-02. Last modified 2026-06-17.