SUSE CVE-2026-6333

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost...

SUSE CVE-2026-6339

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...

CVE-2026-10600

Mattermost versions 11.8.x = 11.8.0, 11.7.x = 11.7.3, 11.6.x = 11.6.5, 10.11.x = 10.11.20 fail to bound the time and resource consumption of server-side document content extraction which allows an authenticated user with file-upload permission to degrade file uploads for all users on the server v...

CVE-2026-9602 Mattermost Desktop App crashes when malformed arguments are provided to some exposed IPC methods

Mattermost Desktop App versions =6.2 6.0.2 5.6.13.0 fail to validate payloads sent from the Mattermost Web App to the Desktop App which allows a malicious server owner to crash the Mattermost Desktop App via changing the payload of a method to a malformed one. Mattermost Advisory ID: MMSA-2026-00...

CVE-2026-6541 Unscoped updates to other playbooks' metric configuration

Mattermost versions 11.7.x = 11.7.1, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict metric configuration changes to the playbook being saved, which allows an authenticated user with team access to alter another user’s playbook metric settings via a crafted import or update request with a...

CVE-2026-9824 Remote cluster metadata enumeration via /share-channel autocomplete

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to check the managesharedchannels permission in the /share-channel autocomplete handler, which allows an authenticated user without that permission to enumerate configured remote cluster connection metadata via slash...

CVE-2026-10103

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing...

CVE-2026-9708 Incoming webhook user attribution via unvalidated webhook owner

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via...

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

PT-2026-52708

The Mattermost Go module github.com/mattermost/mattermost/server/public versions v0.1.22 fail to validate path parameters when constructing API route paths which allows an attacker to redirect API calls to unintended endpoints via crafted IDs containing path traversal components. Mattermost...

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-2026-8074 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 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-2026-9162

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-2026-5139

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...