{"id":"CVE-2018-21257","details":"An issue was discovered in Mattermost Server before 5.1. It allows attackers to bypass intended access restrictions (for setting a channel header) via the Channel header slash command API.","modified":"2026-05-18T10:46:17.646194Z","published":"2020-06-19T17:15:12.740Z","references":[{"type":"ADVISORY","url":"https://mattermost.com/security-updates/"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost","events":[{"introduced":"0"},{"fixed":"54994502241bf40bebd9a9d7719c58f708aef5b1"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"5.1.0"}],"cpe":"cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*","source":"CPE_FIELD"}}],"versions":["v5.1.0-rc3","v5.1.0-rc2","v5.1.0-rc1","v5.0.0-rc1","v4.10.0-rc1","v4.9.0-rc1","v4.8.0-rc1","v4.7.0-rc1","v4.6.0-rc2","v4.6.0-rc1","v4.5.0-rc1","v4.4.0-rc1","v4.3.0-rc1","v4.2.0-rc1","v0.5.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2018-21257.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}