What is the CVSS score of CVE-2026-21483?

CVE-2026-21483 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Listmonk are affected by CVE-2026-21483?

Organizations using listmonk should be aware of moderate risk from CVE-2026-21483, a cross-site scripting vulnerability rated CVSS 5.4.. A patch is available.

Is there a public PoC exploit available for CVE-2026-21483?

Yes, a public proof-of-concept exploit is available for CVE-2026-21483. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-21483?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Listmonk CVE-2026-21483

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-01-02 security-advisories@github.com

GHSA-jmr4-p576-v565

XSS Listmonk Suse Nadh

5.4

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.4 MEDIUM

AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

SUSE

MEDIUM

qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Feb 25, 2026 - 15:20 vuln.today

Public exploit code

CVE Published

Jan 02, 2026 - 21:16 nvd

MEDIUM 5.4

DescriptionGitHub Advisory

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.

AnalysisAI

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. Version 6.0.0 addresses this flaw, though patches are currently unavailable for earlier versions.

Technical ContextAI

Classified as CWE-79 (Cross-site Scripting (XSS)). Affects Listmonk. 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

RemediationAI

Monitor vendor advisories for a patch. Implement output encoding and Content Security Policy headers. Restrict network access to the affected service where possible.