{"id":"CVE-2026-8823","aliases":["GHSA-xmfh-3ccg-c9fx"],"title":"Mattermost has an Incorrect Authorization issue","summary":"Mattermost has an Incorrect Authorization issue","severity":"low","cvss":3.8,"cwe":["CWE-863"],"vendor":"mattermost","product":"github.com/mattermost/mattermost-server","ecosystem":"go","affected":["github.com/mattermost/mattermost-server = 11.7.0","github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.18","github.com/mattermost/mattermost/server/v8 < 8.0.0-20260518160100-9bd77d3fc4d2"],"patched":["github.com/mattermost/mattermost-server 11.7.1","github.com/mattermost/mattermost-server 10.11.18","github.com/mattermost/mattermost/server/v8 8.0.0-20260518160100-9bd77d3fc4d2"],"published":"2026-06-22","updated":"2026-09-22","sourceUpdated":"2026-09-22T14:38:50Z","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-xmfh-3ccg-c9fx","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-8823"},{"url":"https://github.com/mattermost/mattermost/pull/36487"},{"url":"https://github.com/mattermost/mattermost/commit/7972fc53f5c0b0175879a9737308a87b42db1f0b"},{"url":"https://github.com/mattermost/mattermost/commit/9bd77d3fc4d2af3f7f0259a205174e76a1a276e1"},{"url":"https://github.com/mattermost/mattermost/commit/c9bf3609fb9a3e5c2de94c50742c9b91fd723e3d"},{"url":"https://github.com/mattermost/mattermost/commit/d9a55e394cd5bc15edb49e9606bec8fec03ac4c6"},{"url":"https://docs.mattermost.com/security-guide/security-updates"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v10.11.18"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.7.1"},{"url":"https://github.com/advisories/GHSA-xmfh-3ccg-c9fx"}],"tags":["ghsa","go"],"epss":0.00318,"epssPercentile":0.2497,"ingestedAt":"2026-09-22T15:05:01.074Z","slug":"CVE-2026-8823","body":"## Overview\n\nMattermost 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\n\n## Affected packages\n\n- `github.com/mattermost/mattermost-server = 11.7.0`\n- `github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.18`\n- `github.com/mattermost/mattermost/server/v8 < 8.0.0-20260518160100-9bd77d3fc4d2`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/mattermost/mattermost-server 11.7.1`\n- `github.com/mattermost/mattermost-server 10.11.18`\n- `github.com/mattermost/mattermost/server/v8 8.0.0-20260518160100-9bd77d3fc4d2`","depth":"sunlit","depthScore":21,"depthScoreParts":{"impact":20.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}