CVE-2026-34584: CWE-639: Authorization Bypass Through User-Controlled Key in knadh listmonk
A vulnerability in listmonk versions 4. 1. 0 up to but not including 6. 1. 0 allows users in multi-user environments with untrusted users to bypass authorization checks and access mailing lists they should not have access to. This issue arises from bugs in list permission checks. The vulnerability has been patched in version 6. 1. 0. It has a medium severity with a CVSS score of 5.
AI Analysis
Technical Summary
CVE-2026-34584 is an authorization bypass vulnerability in the listmonk newsletter and mailing list manager, affecting versions from 4.1.0 to before 6.1.0. The flaw is due to improper permission checks that allow users in multi-user environments to access mailing lists they are not authorized to view or manage. This vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key). The issue is resolved in version 6.1.0 of listmonk.
Potential Impact
Exploitation of this vulnerability could allow unauthorized users in a multi-user environment to gain access to mailing lists they should not have permission to access. This could lead to unauthorized disclosure of mailing list data and potentially unauthorized actions on those lists. The impact is limited to environments where multiple users with different trust levels share the same listmonk instance. There are no reports of active exploitation in the wild.
Mitigation Recommendations
Upgrade listmonk to version 6.1.0 or later, where this authorization bypass vulnerability has been fixed. Since this is a self-hosted product, administrators should apply the update promptly to mitigate the risk. No additional vendor advisories indicate alternative mitigations or that no action is required.
CVE-2026-34584: CWE-639: Authorization Bypass Through User-Controlled Key in knadh listmonk
Description
A vulnerability in listmonk versions 4. 1. 0 up to but not including 6. 1. 0 allows users in multi-user environments with untrusted users to bypass authorization checks and access mailing lists they should not have access to. This issue arises from bugs in list permission checks. The vulnerability has been patched in version 6. 1. 0. It has a medium severity with a CVSS score of 5.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-34584 is an authorization bypass vulnerability in the listmonk newsletter and mailing list manager, affecting versions from 4.1.0 to before 6.1.0. The flaw is due to improper permission checks that allow users in multi-user environments to access mailing lists they are not authorized to view or manage. This vulnerability is classified under CWE-639 (Authorization Bypass Through User-Controlled Key). The issue is resolved in version 6.1.0 of listmonk.
Potential Impact
Exploitation of this vulnerability could allow unauthorized users in a multi-user environment to gain access to mailing lists they should not have permission to access. This could lead to unauthorized disclosure of mailing list data and potentially unauthorized actions on those lists. The impact is limited to environments where multiple users with different trust levels share the same listmonk instance. There are no reports of active exploitation in the wild.
Mitigation Recommendations
Upgrade listmonk to version 6.1.0 or later, where this authorization bypass vulnerability has been fixed. Since this is a self-hosted product, administrators should apply the update promptly to mitigate the risk. No additional vendor advisories indicate alternative mitigations or that no action is required.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-30T16:56:30.999Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69cead0fe6bfc5ba1df1809d
Added to database: 4/2/2026, 5:53:19 PM
Last enriched: 4/9/2026, 10:53:24 PM
Last updated: 5/20/2026, 9:42:03 PM
Views: 53
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