Answer in brief
CVE-2026-8823 records a Low severity (CVSS 3.8) vulnerability in Mattermost has an Incorrect Authorization issue. The current sources do not mark it as known exploited. The current feed maps github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 3.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go), github.com/mattermost/mattermost-server (go) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/mattermost/mattermost-servergo | =11.7.0 | 11.7.1 |
| github.com/mattermost/mattermost-servergo | >=10.11.0,<10.11.18 | 10.11.18 |
| github.com/mattermost/mattermost-servergo | >=11.7.0 <11.7.1 | 11.7.1 |
| github.com/mattermost/mattermost-servergo | >=10.11.0 <10.11.18 | 10.11.18 |
| github.com/mattermost/mattermost/server/v8go | <8.0.0-20260518160100-9bd77d3fc4d2 | 8.0.0-20260518160100-9bd77d3fc4d2 |
| github.com/mattermost/mattermost/server/v8go | >=0 <8.0.0-20260518160100-9bd77d3fc4d2 | 8.0.0-20260518160100-9bd77d3fc4d2 |
Published upstream
Jun 22, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Sep 22, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Jun 22, 2026
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
Quoted source text, attributed separately from HOL analysis.