Is CVE-2026-34584 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-34584 being exploited in the wild.

How severe is CVE-2026-34584?

Medium severity, with a CVSS score of 5.4, published 2 April 2026.

Which products and versions are affected?

knadh listmonk >= 4.1.0, < 6.1.0.

Is there a fix for CVE-2026-34584?

A patch was published on 2026-03-29: Version 6.1.0 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-34584 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-34584?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-34584: knadh listmonk authorization bypass in list permission checks

Q: Is there a fix for CVE-2026-34584?

A patch was published on 2026-03-29: Version 6.1.0 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-34584 attacked?

It is attacked over the network, in a network appliance.

Q: Am I affected by CVE-2026-34584?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-34584 · Severity: medium · CVSS 5.4 · Published 2026-04-02

listmonk is a self-hosted newsletter and mailing list manager. A security flaw in its permission system allows users in a multi-user environment to access or interact with mailing lists they are not authorized to see. This could lead to unauthorized access to subscriber data or the ability to send unauthorized test emails using restricted lists.

Quick answers

Is CVE-2026-34584 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-34584 being exploited in the wild.
How severe is CVE-2026-34584?: Medium severity, with a CVSS score of 5.4, published 2 April 2026.
Which products and versions are affected?: knadh listmonk >= 4.1.0, < 6.1.0.
Is there a fix for CVE-2026-34584?: A patch was published on 2026-03-29: Version 6.1.0 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-34584 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-34584?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An authorization bypass vulnerability (CWE-639) exists in listmonk due to missing or insufficient permission checks across several API handlers. In multi-user environments, an authenticated attacker with low privileges can bypass intended restrictions to access mailing lists, export subscriber data to JSON, or trigger test emails to subscribers in lists they do not own. The vulnerability specifically impacts campaign updates, CSV imports, bulk subscriber handlers, and the test mail endpoint. The issue is resolved in version 6.1.0 by implementing granular list and subscriber permission filtering.

Affected products

knadh listmonk >= 4.1.0, < 6.1.0

Timeline

2026-03-29: patched: Version 6.1.0 released
2026-03-31: advisory: GitHub Security Advisory published
2026-04-02: disclosed: CVE-2026-34584 published

References

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