CVE-2026-8075

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

CVE-2026-8075

Mattermost Desktop App versions =6.2 5.5.13 6.0.2.0 fail to properly null check when checking for headers in the Mattermost Desktop App which allows any user to crash another channel members Desktop App via posting a malicious link with an embedded image that misses one of those headers. Mattermo...

CVE-2026-9820

Mattermost versions 11.7.x <= 11.7.2 and 10.11.x

EUVD-2026-43308

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-2026-10085 Ordinary group/direct message member can enable group_constrained and remove all channel participants

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4, 10.11.x = 10.11.19 fail to restrict the groupconstrained channel flag to public and private channels that support group synchronization, which allows an ordinary group or direct message member to remove all participants from the conversation v...

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-2026-6062

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 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-2026-8683 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...

CVE-2026-7387 Mattermost group syncable endpoints allow privilege escalation via scheme_admin

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 require role-management authorization when setting the schemeadmin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselv...

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...

PT-2026-48936

Name of the Vulnerable Software and Affected Versions Mattermost versions prior to 11.6.2 Mattermost versions prior to 11.5.5 Mattermost versions prior to 10.11.17 Description A failure to validate that a username returned during bot registration belongs to a bot account allows an unprivileged...

PT-2026-48937

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.6.0 through 11.6.1 Mattermost versions 11.5.0 through 11.5.4 Mattermost versions 10.11.0 through 10.11.16 Description An issue exists where the system fails to enforce the PermissionInviteUser check when setting...

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-2026-6343

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to check public/private permissions which allows members without these permissions to access public playbooks via /get.. Mattermost Advisory ID: MMSA-2026-00591...