{"id":"CVE-2026-82920","aliases":["EUVD-2026-77487","GHSA-v87m-p66q-xcjg"],"status":"published","title":"Mattermost ABAC parent policy bypass via policy update endpoint","description":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724","severity":{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00255,"percentile":0.17226,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2026-09-14T13:59:01Z","modified":"2026-10-28T02:30:31Z","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-2026-82920","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-v87m-p66q-xcjg"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82920.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-82920","title":"Mattermost ABAC parent policy bypass via policy update endpoint","description":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724","status":"published","published":"2026-09-14T13:59:01.993Z","modified":"2026-09-14T19:23:01.097Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T13:40:35.004553Z"}],"euvd":[{"id":"EUVD-2026-77487","description":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724","status":"published","published":"2026-09-14T13:59:01Z","modified":"2026-09-14T19:23:01Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T17:28:19.383429Z"}],"ghsa":[{"id":"GHSA-v87m-p66q-xcjg","title":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce...","description":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724","status":"published","published":"2026-09-14T15:32:46Z","modified":"2026-09-14T15:32:47Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:11:50.762382Z"}],"nvd":[{"id":"CVE-2026-82920","description":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724","status":"published","published":"2026-09-14T14:17:13.01Z","modified":"2026-10-07T18:04:00.843Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:12:46.980627Z"}],"osv":[{"id":"CVE-2026-82920","title":"Mattermost ABAC parent policy bypass via policy update endpoint","description":"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724","status":"published","published":"2026-09-14T13:59:01.993Z","modified":"2026-10-28T02:30:31.258372698Z","cvss":[{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:45:18.482949Z"}]}}