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Known Affected Software Configurations Switch to CPE 2.2

Change History

OR
          *cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* versions from (including) 10.11.0 up to (excluding) 10.11.14
          *cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* versions from (including) 11.4.0 up to (excluding) 11.4.4
          *cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* versions from (including) 11.5.0 up to (excluding) 11.5.2

Mattermost, Inc.: https://mattermost.com/security-updates Types: Vendor Advisory

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, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576

AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CWE-863

https://mattermost.com/security-updates