CVE-2025-3227: 
vulnerability analysis and mitigation

Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, and 10.6.x <= 10.6.5 contain a permission enforcement vulnerability discovered and disclosed on June 20, 2025. The vulnerability affects the channel member management permissions system in playbook runs functionality, allowing authenticated users without proper permissions to manipulate channel membership (NVD, AttackerKB).

The vulnerability stems from improper enforcement of channel member management permissions in playbook runs. When a playbook run is linked to a channel, authenticated users without the 'Manage Channel Members' permission can bypass restrictions to add or remove users from both public and private channels by manipulating playbook run participants. The vulnerability has been assigned a CVSS v3.1 base score of 4.3 (Medium) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N, indicating network accessibility with low attack complexity and requiring low privileges (NVD).

The vulnerability allows authenticated attackers to bypass channel membership controls, potentially leading to unauthorized access management in both public and private channels. This could result in unauthorized users being added to or removed from channels, compromising channel access controls (Wiz).

Organizations should upgrade to the latest version of Mattermost that addresses this vulnerability. The issue has been fixed in versions newer than 10.5.5, 9.11.15, 10.8.0, 10.7.2, and 10.6.5 for their respective release branches (Mattermost Security Updates).