SUSE CVE-2026-6961

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...

GO-2026-6281 Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync in github.com/mattermost/mattermost-server

Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync in github.com/mattermost/mattermost-server...

PT-2026-82030

Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file sync in github.com/mattermost/mattermost-server...

Authorization Bypass Through User-Controlled Key

Overview Affected versions of this package are vulnerable to Authorization Bypass Through User-Controlled Key in the shared channel inbound sync handler. An attacker can modify or delete posts belonging to other users by sending crafted synchronization messages that reference arbitrary post IDs i...

Authorization Bypass Through User-Controlled Key

Overview Affected versions of this package are vulnerable to Authorization Bypass Through User-Controlled Key in the shared channel inbound sync handler. An attacker can modify or delete posts belonging to other users by sending crafted synchronization messages that reference arbitrary post IDs i...

EUVD-2026-43307

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-2026-57654

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...

CVE-2026-10103: Authorization Bypass Through User-Controlled Key

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...

GO-2026-5256 Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server

Mattermost does not verify remote cluster channel access when processing shared channel membership removals in github.com/mattermost/mattermost-server. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. If...

Mattermost Server 10.11.x < 10.11.16 / 11.5.x < 11.5.5 / 11.6.x < 11.6.2 Multiple Vulnerabilities (MMSA-2026-00616 / MMSA-2026-00649 / MMSA-2026-00655 / MMSA-2026-00656 / MMSA-2026-00661 / MMSA-2026-00662 / MMSA-2026-00665)

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

GHSA-8QQ9-CQJ8-82W4 Mattermost doesn't sanitize FileInfo.Name received from federated peers during shared channel file 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 fail 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 within the targ...

CVE-2026-6961

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-2026-6961 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-2026-6961: Improper Limitation of a Pathname to a Restricted Directory

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-2026-6957

Mattermost Plugins versions =1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via...

CVE-2026-6957 Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.

Mattermost Plugins versions =1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via...

CVE-2026-6957: Improper Limitation of a Pathname to a Restricted Directory

Mattermost Plugins versions =1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via...

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,...

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,...

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,...