CVE-2025-53971 — Channel and Team Membership APIs inadvertently allow loss of Member privileges.
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate authorization for team scheme role modifications which allows Team Admins to demote Team Member…
Published: 2025-08-21 · CVSS: 3.8 · CVSS 3.1
Mattermost versions 10.5.x <= 10.5.8, 9.11.x <= 9.11.17 fail to properly validate authorization for team scheme role modifications which allows Team Admins to demote Team Members to Guests via the PUT /api/v4/teams/team-id/members/user-id/schemeRoles API endpoint.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7