Answer in brief
CVE-2026-6689 records a Medium severity (CVSS 4.3) vulnerability in Mattermost doesn't enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation. 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 4.3. 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 | =11.6.0 | 11.6.1 |
| github.com/mattermost/mattermost-servergo | >=11.5.0,<=11.5.4 | 11.5.5 |
| github.com/mattermost/mattermost-servergo | >=10.11.0,<=10.11.15 | 10.11.17 |
| github.com/mattermost/mattermost-servergo | >=11.6.0 <11.6.1 | 11.6.1 |
| github.com/mattermost/mattermost-servergo | >=11.5.0 <11.5.5 | 11.5.5 |
| github.com/mattermost/mattermost-servergo | >=10.11.0 <10.11.17 | 10.11.17 |
| github.com/mattermost/mattermost/server/v8go | >=8.0.0-20250731163400-5b955468ea1e,<8.0.0-20260501144115-7d6816abdfd1 | 8.0.0-20260501144115-7d6816abdfd1 |
| github.com/mattermost/mattermost/server/v8go | >=8.0.0-20250731163400-5b955468ea1e <8.0.0-20260501144115-7d6816abdfd1 | 8.0.0-20260501144115-7d6816abdfd1 |
Published upstream
Jun 12, 2026
Evidence: source:ghsa:source_dates:source-dates:recordSource modified
Aug 24, 2026
Evidence: source:ghsa:source_dates:source-dates:recordFirst seen by HOL
Aug 25, 2026
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Fail to enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation (the check was only applied on update/patch), which allows an authenticated user holding PermissionCreateTeam but not PermissionInviteUser on the resulting team to configure invite-controlled team settings (make the team publicly joinable via open invite and/or constrain membership via allowed domains) that they are not permitted to set on an existing team via POST /api/v4/teams with allow_open_invite: true and/or a non-empty allowed_domains in the request body.. Mattermost Advisory ID: MMSA-2026-00655
Quoted source text, attributed separately from HOL analysis.