SUSE CVE-2026-28741

Mattermost versions 10.11.x = 10.11.12, 11.5.x = 11.5.0, 11.4.x = 11.4.2, 11.3.x = 11.3.2 fail to validate CSRF tokens on an authentication endpoint which allows an attacker to update a user's authentication method via a CSRF attack by tricking a user into visiting a malicious page. Mattermost...

CVE-2026-8075

CVE-2026-8075 concerns the Mattermost Desktop App. The connected details specify that versions

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...

EUVD-2026-43340

Mattermost versions 11.7.x = 11.7.2, 10.11.x = 10.11.19 fail to sanitize team objects returned by the scheme teams endpoint, which allows a user with the User Manager role to obtain invite links for private teams and use them to join or share access to those teams via the scheme teams API...

CVE-2026-10106 Unauthorized users can trigger interactive post actions in private channels via action cookie channel mismatch in Mattermost

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to verify that the channel referenced in an action cookie matches the channel of the target post, which allows an authenticated user without access to a private channel to trigger interactive post actions on posts in th...

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...

PT-2026-57654

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...

PT-2026-57661

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to validate the length and content of message attachment field values, which allows an authenticated attacker to cause a denial of service for all users in a channel via a post containing a specially crafted payload tha...

CVE-2026-3472 Markdown image rendering bypass in AI bot tool result posts in Mattermost

Mattermost versions 10.11.x = 10.11.18, 11.6.x = 11.6.3, 11.5.x = 11.5.6 fail to properly apply markdown image rendering restrictions to AI bot tool result posts, which allows an authenticated attacker to exfiltrate data to an attacker-controlled server via injecting markdown image syntax into to...

CVE-2026-8683 Overly long URLs crash the Mattermost Desktop App

Mattermost Desktop App versions =6.1 5.5.13.0 fail to account for attempting to open extremely long URLs in the Mattermost Desktop App which allows a malicious server owner to crash the application via including a script to call window.open on a very large URL. Mattermost Advisory ID:...

CVE-2026-6517 Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed

Mattermost Desktop App versions =6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that...

PT-2026-49238

Name of the Vulnerable Software and Affected Versions Mattermost Desktop App versions prior to 6.1 Mattermost Desktop App version 5.5.13.0 Description The application fails to restrict the allow list of domains for NTLM credential forwarding. This allows a user on a server where the image proxy i...

CVE-2026-3433

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 fail to restrict roleupdated websocket event broadcasts to members of the affected team or channel which allows an authenticated attacker with guest-level access to observe permission scheme change...

EUVD-2026-36501

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 Fail to enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation the check was only applied on update/patch, which allows an authenticated user holding...

CVE-2026-3117

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to properly check for permissions when processing commands in the Gitlab plugin which allows normal users to uninstall instances or setup webhook connections via the gitlab instance option or the /gitlab webhook option commands...

CVE-2026-6342

Mattermost Plugins versions =11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID:...

CVE-2026-28735

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 the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL...

GHSA-R5VF-GRCX-5VQP Mattermost allows authenticated users to gain access to private repositories

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 the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL...

GHSA-W9M8-P4CC-4QJ9 Mattermost doesn't properly validate msgpack-encoded WebSocket frames before memory allocation

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 properly validate msgpack-encoded WebSocket frames before memory allocation which allows an unauthenticated remote attacker to crash the server process and cause a full service outage for all users v...

GHSA-PG7C-462J-GRXV Mattermost doesn't archive the channel before removing persistent notifications

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...