CVE-2026-21483
MEDIUM
GHSA-jmr4-p576-v565
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
4Description
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.
Analysis
Stored XSS in Listmonk before version 6.0.0 allows authenticated users with campaign management permissions to inject malicious JavaScript that executes when administrators preview campaigns or templates, enabling privilege escalation attacks such as creating backdoor admin accounts. Public exploit code exists for this vulnerability, and the attack surface expands through the public archive feature where victims need only visit a link to trigger the payload. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.
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External POC / Exploit Code
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