CVE-2025-25279

Security Advisory MMSA-2025-00430 / CVE-2025-25279 Summary After uploading a file to Mattermost Boards, when the fileId parameter is modified and the board is copied, the file now points to and downloads the target file specified in the parameter. Affected Versions: Mattermost instances with Boar...

CVE-2026-13417

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 validate the type of fields.properties on block creation which allows an authenticated user with editor access to a board to crash the Boards plugin worker and trigger a denial of service via a child...

CVE-2026-13417 Boards plugin denial of service via unvalidated block fields.properties

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 validate the type of fields.properties on block creation which allows an authenticated user with editor access to a board to crash the Boards plugin worker and trigger a denial of service via a child...

EUVD-2026-77376

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 validate the type of fields.properties on block creation which allows an authenticated user with editor access to a board to crash the Boards plugin worker and trigger a denial of service via a child...

CVE-2026-13417

Mattermost Boards plugin denial of service vulnerability in versions 11.9.x ≤ 11.9.0 , 11.8.x ≤ 11.8.4 , 11.7.x ≤ 11.7.7 , and 10.11.x ≤ 10.11.22 . The plugin fails to validate the type of fields.properties on block creation, allowing an authenticated user with editor access to a board to crash t...

CVE-2026-14344 Inconsistent authorization checks in Mattermost Boards endpoints

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 enforce the board-creation permission which allows an unauthorized authenticated user to create boards via the board duplicate, boards-and-blocks, and archive-import endpoints.. Mattermost Advisory I...

CVE-2026-14344 Inconsistent authorization checks in Mattermost Boards endpoints

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 enforce the board-creation permission which allows an unauthorized authenticated user to create boards via the board duplicate, boards-and-blocks, and archive-import endpoints.. Mattermost Advisory I...

PT-2026-91143

Name of the Vulnerable Software and Affected Versions Mattermost version 11.9.0 Mattermost version 11.8.4 Mattermost version 11.7.7 Mattermost version 10.11.22 Description An issue exists where the software fails to validate the type of fields.properties during block creation. This allows an...

CVE-2026-9859 Mattermost Boards plugin didn’t enforce role-based authorization on board channel link allowing board editors to expose boards to arbitrary channels

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...

CVE-2026-9859 Mattermost Boards plugin didn’t enforce role-based authorization on board channel link allowing board editors to expose boards to arbitrary channels

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...

CVE-2026-9859 Mattermost Boards plugin didn’t enforce role-based authorization on board channel link allowing board editors to expose boards to arbitrary channels

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...

CVE-2026-9859

Mattermost Boards plugin (versions ≤11.7.6, ≤10.11.21, ≤11.8.3) fails to enforce PermissionManageBoardRoles on the batch endpoint's channelId field, allowing authenticated board editors to relink boards to arbitrary channels via crafted PATCH requests. CVSS 3.1 scores 6.5 (MEDIUM) for network-bas...

CVE-2026-10080 Boards plugin panics on WebSocket command with non-string field types

Mattermost versions 11.7.x = 11.7.6, 10.11.x = 10.11.21, 11.8.x = 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a customfocalboardSUBSCRIBETEAM message with a non-string teamId...

CVE-2026-10080 Boards plugin panics on WebSocket command with non-string field types

Mattermost versions 11.7.x = 11.7.6, 10.11.x = 10.11.21, 11.8.x = 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a customfocalboardSUBSCRIBETEAM message with a non-string teamId...

GO-2026-4782 Mattermost Boards Plugin fails to implement authorisation checks on comment block modifications in github.com/mattermost/mattermost-plugin-boards

Mattermost Boards Plugin fails to implement authorisation checks on comment block modifications in github.com/mattermost/mattermost-plugin-boards...

Mattermost Boards Plugin fails to implement authorisation checks on comment block modifications

Mattermost Plugins versions =11.3 11.0.3 11.2.2 10.10.11.0 fail to implement authorisation checks on comment block modifications, which allows an authorised attacker with editor permission to modify comments created by other board members. Mattermost Advisory ID: MMSA-2025-00559...

CVE-2023-40703

Mattermost fails to properly limit the characters allowed in different fields of a block in Mattermost Boards allowing a attacker to consume excessive resources, possibly leading to Denial of Service, by patching the field of a block using a specially crafted string...

GHSA-58W6-W55X-6WQ8 Mattermost fails to validate user permissions in Boards

Mattermost versions 10.11.x = 10.11.4, 10.5.x = 10.5.12 fail to validate the user permission when accessing the files and subscribing to the block in Boards, which allows an authenticated user to access other board files and was able to subscribe to the block from other boards that the user does...

CVE-2025-13870 Unauthorized access and subscription vulnerability in Boards

Mattermost versions 10.11.x = 10.11.4, 10.5.x = 10.5.12 fail to validate the user permission when accessing the files and subscribing to the block in Boards, which allows an authenticated user to access other board files and was able to subscribe to the block from other boards that the user does...

CVE-2025-12756 Insecure Direct Object Reference in Mattermost Boards Plugin Enables Unauthorised Comment Deletion

Mattermost versions 11.0.x = 11.0.2, 10.12.x = 10.12.1, 10.11.x = 10.11.4, 10.5.x = 10.5.12 fail to validate user permissions when deleting comments in Boards, which allows an authenticated user with the editor role to delete comments created by other users...