Mattermost: >> Mattermost Server >> 10.11.21 Security Vulnerabilities
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin flags with a user's current role which allows a user demoted to System Guest to retain Board Admin privileges and perform admin-only operations via the Boards REST API or UI.. Mattermost Advisory ID: MMSA-2026-00691
CVSS Score
6.3
EPSS Score
0.003
Published
2026-08-17
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672
CVSS Score
5.4
EPSS Score
0.003
Published
2026-08-17
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 Mattermost failed to restrict OAuth deauthorization and personal access token management endpoints to direct user sessions, which allowed an OAuth app with a delegated user token to revoke the user's authorizations or tokens for other integrations via account-management endpoints.. Mattermost Advisory ID: MMSA-2026-00704
CVSS Score
4.3
EPSS Score
0.003
Published
2026-08-17
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to limit decompressed content size and enforce the configured maximum file size in the Boards archive import handler, which allows an authenticated user to cause memory exhaustion or unbounded disk consumption via a crafted .boardarchive file uploaded to the import endpoint.. Mattermost Advisory ID: MMSA-2026-00713
CVSS Score
6.5
EPSS Score
0.004
Published
2026-08-13
Mattermost versions <11.0 fail to properly enforce the "Allow users to view archived channels" setting which allows regular users to access archived channel content and files via the "Open in Channel" functionality from followed threads
CVSS Score
3.1
EPSS Score
0.002
Published
2025-11-14
Mattermost versions <11 fail to enforce multi-factor authentication on WebSocket connections which allows unauthenticated users to access sensitive information via WebSocket events
CVSS Score
6.5
EPSS Score
0.003
Published
2025-11-14
Mattermost versions <11 fail to properly restrict access to archived channel search API which allows guest users to discover archived public channels via the `/api/v4/teams/{team_id}/channels/search_archived` endpoint
CVSS Score
4.3
EPSS Score
0.002
Published
2025-11-14
Page 3