VDB
CVE-2026-9859
CVE-2026-9859
PUBLISHED
CVSS 6.5 MEDIUM
Reported by Mattermost · Published August 17, 2026
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to enforce PermissionManageBoardRoles on the channelId field of the batch endpoint, which allows an authenticated board editor to relink any board they can edit to an arbitrary channel via a crafted PATCH request. Mattermost Advisory ID: MMSA-2026-00686
Risk Scores
CVSS 3.1
6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost | 11.7.0, 10.11.0, 11.8.0 |
| Mattermost | Mattermost | 11.7.0, 10.11.0, 11.8.0 |
Timeline
- Aug 17, 2026 CVE Published
- Aug 18, 2026 Coalition ESS Score
- Aug 18, 2026 CVE Updated
- Aug 24, 2026 EPSS Score
- Aug 30, 2026 EPSS Score
References
- MMSA-2026-00686 vendor-advisory