CVE-2026-9859

Summary

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

Affected Software

VendorProductVersion RangeStatus
MattermostMattermost11.7.0 <= 11.7.6affected
MattermostMattermost10.11.0 <= 10.11.21affected
MattermostMattermost11.8.0 <= 11.8.3affected
MattermostMattermost11.9.0unaffected
MattermostMattermost11.7.7unaffected
MattermostMattermost10.11.22unaffected
MattermostMattermost11.8.4unaffected

Weaknesses

  • CWE-863: CWE-863: Incorrect Authorization

References