{"id":"CVE-2026-15754","aliases":["EUVD-2026-60212","GHSA-mg83-f953-3vq5"],"status":"published","title":"Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal","description":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718","severity":{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00246,"percentile":0.15903,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2026-08-17T14:36:56Z","modified":"2026-10-28T02:31:00Z","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-2026-15754","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-mg83-f953-3vq5"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/15xxx/CVE-2026-15754.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-15754","title":"Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal","description":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718","status":"published","published":"2026-08-17T14:36:56.282Z","modified":"2026-08-17T15:25:38.145Z","cvss":[{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T13:47:51.033687Z"}],"euvd":[{"id":"EUVD-2026-60212","description":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718","status":"published","published":"2026-08-17T14:36:56Z","modified":"2026-08-17T15:25:38Z","cvss":[{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T18:01:49.335011Z"}],"ghsa":[{"id":"GHSA-mg83-f953-3vq5","title":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign...","description":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718","status":"published","published":"2026-08-17T15:30:40Z","modified":"2026-08-17T15:30:41Z","cvss":[{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:10:34.652326Z"}],"nvd":[{"id":"CVE-2026-15754","description":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718","status":"published","published":"2026-08-17T15:16:53.743Z","modified":"2026-08-18T20:24:58.563Z","cvss":[{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:12:38.647684Z"}],"osv":[{"id":"CVE-2026-15754","title":"Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal","description":"Mattermost versions 11.7.x \u003c= 11.7.6, 11.8.x \u003c= 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC (attribute-based access control) policy assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718","status":"published","published":"2026-08-17T14:36:56.282Z","modified":"2026-10-28T02:31:00.243927118Z","cvss":[{"version":"3.1","score":4.2,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:44:57.682091Z"}]}}