istmonk 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.
| Link | Resource |
|---|---|
| https://github.com/knadh/listmonk/security/advisories/GHSA-jmr4-p576-v565 | Exploit Vendor Advisory |
25 Feb 2026, 15:20
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:a:nadh:listmonk:*:*:*:*:*:*:*:* | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.4 |
| References | () https://github.com/knadh/listmonk/security/advisories/GHSA-jmr4-p576-v565 - Exploit, Vendor Advisory | |
| First Time |
Nadh
Nadh listmonk |
02 Jan 2026, 21:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Published : 2026-01-02 21:16
Updated : 2026-02-25 15:20
NVD link : CVE-2026-21483
Mitre link : CVE-2026-21483
CVE.ORG link : CVE-2026-21483
JSON object : View
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')