CVE-2026-9824

Mattermost v11.7.x ≤ 11.7.2, v11.6.x ≤ 11.6.4, and v10.11.x ≤ 10.11.19 are affected by CVE-2026-9824 due to a missing check of the manage_shared_channels permission in the /share-channel autocomplete handler. This allows an authenticated user without that permission to enumerate remote cluster co...

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-2026-10103 Authenticated remote cluster can modify or delete posts it does not own in Mattermost Connected Workspaces shared channels

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-2026-10103

Mattermost versions affected: 11.7.x (up to 11.7.2), 11.6.x (up to 11.6.4), and 10.11.x (up to 10.11.19) have a flaw in the shared channel inbound sync handler that fails to verify post ownership. This allows an authenticated remote cluster to modify or delete posts authored by local users or oth...

GHSA-XG3J-C7Q4-F9PH Canonical MicroCeph: path traversal issue in the remote-import AP

Canonical MicroCeph versions from the squid and tentacle track are vulnerable to a path traversal issue in the remote-import API. Holders of a trusted cluster mTLS certificate such as enrolled cluster members or join token can manipulate files in an imported remote cluster within the...

CVE-2026-10720

Canonical MicroCeph versions from the squid and tentacle track are vulnerable to a path traversal issue in the remote-import API. Holders of a trusted cluster mTLS certificate such as enrolled cluster members or join token can manipulate files in an imported remote cluster within the...

PT-2026-50835

Name of the Vulnerable Software and Affected Versions Canonical MicroCeph versions from the squid and tentacle track Description A path traversal issue exists in the remote-import API. Users possessing a join token or a trusted cluster mTLS certificate, such as enrolled cluster members, can...

CVE-2026-7184

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users with the managesecureconnections permission to obtain remote cluster authentication tokens via a PATCH request to the...

CVE-2026-7184 Mattermost Remote Cluster PATCH API Leaks Authentication Tokens

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users with the managesecureconnections permission to obtain remote cluster authentication tokens via a PATCH request to the...

CVE-2026-7184 Mattermost Remote Cluster PATCH API Leaks Authentication Tokens

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users with the managesecureconnections permission to obtain remote cluster authentication tokens via a PATCH request to the...

CVE-2026-7184 Mattermost Remote Cluster PATCH API Leaks Authentication Tokens

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users with the managesecureconnections permission to obtain remote cluster authentication tokens via a PATCH request to the...

CVE-2026-7184

Mattermost CVE-2026-7184 affects Mattermost versions 11.6.x up to 11.6.1, 11.5.x up to 11.5.4, and 10.11.x up to 10.11.15. The issue is a failure to sanitize the Remote Cluster API response on PATCH operations, allowing authenticated users with the {{manage_secure_connections}} permission to obta...

EUVD-2026-36500

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users with the managesecureconnections permission to obtain remote cluster authentication tokens via a PATCH request to the...

PT-2026-48940

Mattermost versions 11.6.x = 11.6.1, 11.5.x = 11.5.4, 10.11.x = 10.11.15 fail to sanitize the Remote Cluster API response on PATCH operations, which allows authenticated users with the manage secure connections permission to obtain remote cluster authentication tokens via a PATCH request to the...

CVE-2026-4273

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate that the RefreshedToken differs from the original invite token during remote cluster invite confirmation which allows an authenticated attacker to bypass token rotation and reuse the original invite token via sending a craft...

CVE-2026-28759

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel,...

Mattermost Server 10.11.x <= 10.11.13 / 11.5.x <= 11.5.1 Multiple Vulnerabilities (MMSA-2026-00570 / MMSA-2026-00575 / MMSA-2026-00582 / MMSA-2026-00622)

The version of Mattermost Server installed on the remote host is affected by multiple vulnerabilities: - Mattermost fails 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...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization via the membership sync process. An attacker can remove users from any channel, including private channels, by sending crafted membership sync messages from a remote cluster that is not authorized to access the...

GHSA-8H9W-W78C-VVR3 Mattermost does not verify remote cluster channel access when processing shared channel membership removals

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13, 11.4.x = 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel,...

GHSA-HQPJ-F3JH-29VX Mattermost doesn't validate that the RefreshedToken differs from the original invite token during remote cluster invite confirmation

Mattermost versions 11.5.x = 11.5.1, 10.11.x = 10.11.13 fail to validate that the RefreshedToken differs from the original invite token during remote cluster invite confirmation which allows an authenticated attacker to bypass token rotation and reuse the original invite token via sending a craft...