CVE-2026-9859

EUVD-2026-60541
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
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
MattermostCNA
6.5 MEDIUM
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 25.11%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.22
mattermostmattermost_server
11.7.0 ≤
𝑥
< 11.7.7
mattermostmattermost_server
11.8.0 ≤
𝑥
< 11.8.4
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
11.7.0 ≤
𝑥
≤ 11.7.6
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.21
CNA
mattermostmattermost
11.8.0 ≤
𝑥
≤ 11.8.3
CNA