{"id":"CVE-2025-53971","aliases":["GHSA-4276-cm8c-788h","GO-2025-3902"],"url":"https://o3.security/vulnerability/CVE-2025-53971","summary":"Channel and Team Membership APIs inadvertently allow loss of Member privileges.","details":"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.","published":"2025-08-21T07:31:01.870Z","modified":"2026-08-12T03:51:18.713225041Z","cvss":{"score":3.8,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N"},"epss":{"score":0.00203,"percentile":0.10153,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"10.5.9"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"9.11.18"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20250721095846-c602a4a78e1f"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v5","fixedVersion":null},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server/v6","fixedVersion":null}],"fix":null,"references":[{"type":"WEB","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/53xxx/CVE-2025-53971.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-53971"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:18.713225041Z"}}