{"id":"CVE-2026-26230","aliases":["EUVD-2026-12518","GHSA-q6ph-8227-6m8x"],"status":"published","title":"Team Admin Privilege Escalation to Demote Members to Guest","description":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531","severity":{"version":"3.1","score":3.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00185,"percentile":0.08179,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2026-03-16T20:19:51Z","modified":"2026-10-28T02:30:28Z","products":[{"vendor":"mattermost","product":"mattermost"},{"vendor":"mattermost","product":"mattermost_server"}],"references":[{"url":"https://mattermost.com/security-updates","tags":["vendor-advisory","Vendor Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26230","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-q6ph-8227-6m8x"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26230.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-26230","title":"Team Admin Privilege Escalation to Demote Members to Guest","description":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531","status":"published","published":"2026-03-16T20:19:51.287Z","modified":"2026-03-17T13:37:17.914Z","cvss":[{"version":"3.1","score":3.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N","level":"low","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T13:38:20.971157Z"}],"euvd":[{"id":"EUVD-2026-12518","description":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531","status":"published","published":"2026-03-16T20:19:51Z","modified":"2026-03-17T13:37:17Z","cvss":[{"version":"3.1","score":3.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N","level":"low"}],"updated_at":"2026-11-02T19:25:33.692584Z"}],"ghsa":[{"id":"GHSA-q6ph-8227-6m8x","title":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the...","description":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531","status":"published","published":"2026-03-16T21:34:33Z","modified":"2026-03-16T21:34:42Z","cvss":[{"version":"3.1","score":3.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N","level":"low"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:06:39.944141Z"}],"nvd":[{"id":"CVE-2026-26230","description":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531","status":"published","published":"2026-03-16T21:16:33.48Z","modified":"2026-06-17T10:25:59.007Z","cvss":[{"version":"3.1","score":3.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N","level":"low","assessor":"secondary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:12:09.735529Z"}],"osv":[{"id":"CVE-2026-26230","title":"Team Admin Privilege Escalation to Demote Members to Guest","description":"Mattermost versions 10.11.x \u003c= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531","status":"published","published":"2026-03-16T20:19:51.287Z","modified":"2026-10-28T02:30:28.781325164Z","cvss":[{"version":"3.1","score":3.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N","level":"low"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:44:59.80315Z"}]}}