Vulnerability · Published Jun 22, 2026 · Assigned by Mattermost
CVE-2026-8823User Manager can demote bot accounts to guest without bot-management permission
Low 3.8
In plain English
A low-severity incorrect authorization in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)3.8Low
Exploit odds (30 days)0.3%top 75.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | 10.11.18+incompatible, 11.7.1+incompatible | GO-2026-6547 |
| Go | github.com/mattermost/mattermost-server | 10.11.18 | GHSA-xmfh-3ccg-c9fx |
| Go | github.com/mattermost/mattermost-server | 11.7.1 | GHSA-xmfh-3ccg-c9fx |
| Go | github.com/mattermost/mattermost-server/v5 | no fix listed | GO-2026-6547 |
| Go | github.com/mattermost/mattermost-server/v6 | no fix listed | GO-2026-6547 |
| Go | github.com/mattermost/mattermost/server/v8 | 8.0.0-20260518160100-9bd77d3fc4d2 | GO-2026-6547 |
| Go | github.com/mattermost/mattermost/server/v8 | 8.0.0-20260518160100-9bd77d3fc4d2 | GHSA-xmfh-3ccg-c9fx |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 11.7.0 – through 11.7.010.11.0 – through 10.11.17 |
Weakness: CWE-863 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L
References
- MMSA-2026-00669 vendor-advisory