CVE-2026-14298

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 properly limit resource consumption when processing certain user-supplied input, which allows an authenticated user to cause a denial of service. Mattermost Advisory ID: MMSA-2026-00713...

EUVD-2026-57742

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 properly limit resource consumption when processing certain user-supplied input, which allows an authenticated user to cause a denial of service. Mattermost Advisory ID: MMSA-2026-00713...

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-2026-8075

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

CVE-2026-9820

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

CVE-2026-9820 Mattermost schemes teams endpoint exposes private team invite IDs

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...

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-2026-9597 Deactivated guest accounts can authenticate via magic-link token in Mattermost REST API login endpoint

Mattermost versions 11.7.x = 11.7.2, 11.6.x = 11.6.4 fail to verify whether a guest account is deactivated before creating a session in the magic-link token login path, which allows a deactivated guest user to obtain a fully functional session via a magic-link token issued prior to deactivation...

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-2026-10085 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...