What is CVE-2026-34584?

CVE-2026-34584 is a medium-severity vulnerability in Knadh Listmonk, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 5.4/10. Published 2026-04-02.

How severe is CVE-2026-34584?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Auth bypass in Knadh Listmonk

CVE-2026-34584

listmonk is a standalone, self-hosted, newsletter and mailing list manager. From version 4.1.0 to before version 6.1.0, bugs in list permission checks allows users in a multi-user environment to access to lists (which they don't have access to) under different scenarios. This only affects multi-user environments with untrusted users. This issue has been patched in version 6.1.0.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2026-04-02 · last modified 2026-07-24.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (19.8th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 19.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Knadh Listmonk — versions >= 4.1.0, < 6.1.0
Nadh Listmonk

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

github.com/knadh/listmonk/security/advisories/GHSA-85j8-5c6w-gcpv (Patch, Vendor Advisory)
github.com/knadh/listmonk/commit/347f5976759232c36e571cf58b4bfe33c2794f35 (Patch)
github.com/knadh/listmonk/releases/tag/v6.1.0 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-34584?: CVE-2026-34584 is a medium-severity vulnerability in Knadh Listmonk, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 5.4/10. Published 2026-04-02.
How severe is CVE-2026-34584?: Medium severity. CVSS v3 base score is 5.4 out of 10.