CVE-2026-8823
Low
Description
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
SeverityLow
CVSS3.8
Exploit probability—
Product
Mattermost Server
PublishedJun 22, 2026
First seenJun 22, 2026
Weakness typeCWE-863Incorrect authorization
How to fix
Update
- mattermost mattermost_server10.11.18, 11.7.1 or later
- github.com/mattermost/mattermost-server11.7.1, 10.11.18, 10.11.18+incompatible, 11.7.1+incompatible or later
- github.com/mattermost/mattermost/server/v88.0.0-20260518160100-9bd77d3fc4d2 or later
Vendor advisories
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.18, 11.7.0 ≤ v < 11.7.1 | 10.11.18, 11.7.1 |
| github.com/mattermost/mattermost-serverGo | 11.7.0 ≤ v < 11.7.1, 10.11.0 ≤ v < 10.11.18, 10.11.0+incompatible ≤ v < 10.11.18+incompatible, 11.7.0+incompatible ≤ v < 11.7.1+incompatible | 11.7.1, 10.11.18, 10.11.18+incompatible, 11.7.1+incompatible |
| github.com/mattermost/mattermost/server/v8Go | v < 8.0.0-20260518160100-9bd77d3fc4d2 | 8.0.0-20260518160100-9bd77d3fc4d2 |
| github.com/mattermost/mattermost-server/v5Go | No range specified | — |
| github.com/mattermost/mattermost-server/v6Go | No range specified | — |
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