{"id":"CVE-2026-20796","details":"Mattermost versions 10.11.x \u003c= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549","aliases":["GHSA-2xf7-hmf6-p64j","GO-2026-4495"],"modified":"2026-04-10T05:38:19.462223Z","published":"2026-02-13T11:16:10.280Z","related":["SUSE-SU-2026:0757-1"],"references":[{"type":"ADVISORY","url":"https://mattermost.com/security-updates"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost-server","events":[{"introduced":"5b955468ea1ea8b56c0fb10feb258a36a767d7bb"},{"fixed":"ba27ba1f8cb1ffe2b1a79dc3d15a3ffa7de12fd7"}],"database_specific":{"versions":[{"introduced":"10.11.0"},{"fixed":"10.11.10"}]}}],"versions":["@mattermost/client@10.11.0","@mattermost/types@10.11.0","mattermost-redux@10.11.0","v10.11.0","v10.11.0-rc3","v10.11.1","v10.11.1-rc1","v10.11.2","v10.11.2-rc1","v10.11.2-rc2","v10.11.3","v10.11.4","v10.11.4-rc1","v10.11.4-rc2","v10.11.4-rc3","v10.11.5","v10.11.6","v10.11.7","v10.11.8","v10.11.9","v10.11.9-rc1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-20796.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N"}]}