CVE-2026-8823: Mattermost has an Incorrect Authorization issue
(updated )
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
References
- docs.mattermost.com/security-guide/security-updates
- github.com/advisories/GHSA-xmfh-3ccg-c9fx
- github.com/mattermost/mattermost/commit/7972fc53f5c0b0175879a9737308a87b42db1f0b
- github.com/mattermost/mattermost/commit/9bd77d3fc4d2af3f7f0259a205174e76a1a276e1
- github.com/mattermost/mattermost/commit/c9bf3609fb9a3e5c2de94c50742c9b91fd723e3d
- github.com/mattermost/mattermost/commit/d9a55e394cd5bc15edb49e9606bec8fec03ac4c6
- github.com/mattermost/mattermost/pull/36487
- github.com/mattermost/mattermost/releases/tag/v10.11.18
- github.com/mattermost/mattermost/releases/tag/v11.7.1
- nvd.nist.gov/vuln/detail/CVE-2026-8823
Code Behaviors & Features
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