CVE-2026-3472

CVE-2026-3472 affects Mattermost where specific versions (10.11.x <= 10.11.18, 11.6.x <= 11.6.3, 11.5.x

CVE-2026-6062

CVE-2026-6062 affects Mattermost versions 11.7.x ≤ 11.7.0, 11.6.x ≤ 11.6.2, 11.5.x ≤ 11.5.5, and 10.11.x ≤ 10.11.17. The issue is a logic flaw where the system fails to validate channel ownership of an existing subscription before applying edits, enabling an authenticated attacker to hijack subsc...

CVE-2026-8074 Improper Permission Check Allows User Manager to Deactivate Bot Accounts

Mattermost versions 11.7.x = 11.7.0, 10.11.x = 10.11.17 fail to enforce bot-specific permission checks on the user active status endpoint, which allows a User Manager with user management write access but no Integrations access to deactivate bot accounts via the PUT /api/v4/users/id/active API...

CVE-2026-9162

Mattermost versions 11.7.x = 11.7.0, 11.6.x = 11.6.2, 11.5.x = 11.5.5, 10.11.x = 10.11.17 fail to invalidate cached authentication state for active WebSocket connections during global session revocation, which allows a user with an existing WebSocket connection to remain authenticated and continu...

CVE-2026-9162

Mattermost vulnerability CVE-2026-9162 affects Mattermost versions 11.7.x ≤ 11.7.0, 11.6.x ≤ 11.6.2, 11.5.x ≤ 11.5.5, 10.11.x ≤ 10.11.17. The issue: global session revocation does not invalidate cached authentication state for active WebSocket connections, allowing a user with an existing WebSock...

CVE-2026-5139

Mattermost plugin vulnerability CVE-2026-5139 affects Mattermost versions 11.7.x ≤ 11.7.0, 11.6.x ≤ 11.6.2, 11.5.x ≤ 11.5.5, 10.11.x ≤ 10.11.17. The issue arises in the /gitlab connect command handler where administrator authorization is not enforced for the setDefaultInstance call, allowing any ...

CVE-2026-6961 CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15, 10.11.x = 10.11.16 Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server to write files to arbitrary locations...

CVE-2026-4286

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to check if teamid was being changed when updating playbooks, allowing users with only Manage Playbook Configurations permission to change a playbook's team, bypassing manage members restriction via PUT api. Mattermost Advisory ID:...

CVE-2026-5163

Mattermost versions 11.5.x = 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite...

CVE-2026-4635

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting...

PT-2026-44032

Name of the Vulnerable Software and Affected Versions Mattermost Plugins versions prior to 1.1.6 Description Insufficient sanitization of filenames received from federated peers when constructing export destination paths allows a remote administrator of a federated server to perform a path...

CVE-2026-28735

Mattermost versions 10.11.x up to 10.11.14, 11.4.x up to 11.4.4, 11.5.x up to 11.5.3, and 11.6.x up to 11.6.0 fail to validate the OAuth token scope on the callback, enabling an authenticated Mattermost user to gain access to private repositories by modifying the scope parameter in the GitHub aut...

CVE-2026-3473 Improper file ownership validation in the Boards API allows unauthorised file access

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs...

CVE-2026-4646

Mattermost has an input-validation flaw in the API request handlers used by the PR details endpoint. Affected versions are 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, and 10.11.x

CVE-2026-3636

Mattermost CVE-2026-3636 affects versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, and 10.11.x

CVE-2026-4858 Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action...

CVE-2026-4858

Mattermost CVE-2026-4858 affects versions 11.6.x, 11.5.x, 11.4.x and 10.11.x where the integration action URL does not properly validate path traversal. This allows a malicious authenticated user to call an arbitrary API using the system admin Mattermost token by exploiting the path traversal in ...

CVE-2026-4858 Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.

Mattermost versions 11.6.x = 11.6.0, 11.5.x = 11.5.3, 11.4.x = 11.4.4, 10.11.x = 10.11.14 fail to check integration URL for path traversal which allows an malicious authenticated user to call an arbitrary API via system admin Mattermost auth token using via path traversal in integration action...

Mattermost doesn't validate the X-Requested-With header on the burn-on-read reveal endpoint

Mattermost versions 11.5.x = 11.5.1, 11.4.x = 11.4.3 fail to validate the X-Requested-With header on the burn-on-read reveal endpoint which allows an authenticated channel member to force the reveal of a burn-on-read message without recipient consent via a crafted Markdown image tag.. Mattermost...

GHSA-9P64-JPC7-M2RP Mattermost doesn't sanitize sensitive configuration fields before including them in support packet generation

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to sanitize sensitive configuration fields before including them in support packet generation, which allows a Mattermost System Admin or any party with access to a support packet to obtain sensitive credentials in...