{"id":"CVE-2026-8823","aliases":["GHSA-xmfh-3ccg-c9fx","GO-2026-6547"],"url":"https://o3.security/vulnerability/CVE-2026-8823","summary":"User Manager can demote bot accounts to guest without bot-management permission","details":"Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669","published":"2026-06-22T13:41:28.404Z","modified":"2026-10-21T03:00:02.394250760Z","cvss":{"score":3.8,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.7.1"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"10.11.18"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20260518160100-9bd77d3fc4d2"}],"fix":{"url":"https://github.com/mattermost/mattermost/pull/36487","label":"mattermost/mattermost#36487"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8823.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-8823"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/pull/36487"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/7972fc53f5c0b0175879a9737308a87b42db1f0b"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/9bd77d3fc4d2af3f7f0259a205174e76a1a276e1"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/c9bf3609fb9a3e5c2de94c50742c9b91fd723e3d"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/commit/d9a55e394cd5bc15edb49e9606bec8fec03ac4c6"},{"type":"WEB","url":"https://docs.mattermost.com/security-guide/security-updates"},{"type":"PACKAGE","url":"https://github.com/mattermost/mattermost"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/releases/tag/v10.11.18"},{"type":"WEB","url":"https://github.com/mattermost/mattermost/releases/tag/v11.7.1"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T03:00:02.394250760Z"}}