{"id":"CVE-2026-3115","summary":"Guest users can view group member IDs without respecting view restrictions","details":"Mattermost versions 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 10.11.10, 11.4.x \u003c= 11.4.0, 11.3.x \u003c= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594","aliases":["GHSA-mpc7-mm28-f6wq","GO-2026-5512"],"modified":"2026-08-12T03:51:23.011450972Z","published":"2026-03-26T16:23:05.887Z","related":["openSUSE-SU-2026:21483-1"],"database_specific":{"cna_assigner":"Mattermost","cwe_ids":["CWE-863"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3115.json","unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"11.2.0"},{"last_affected":"11.2.2"},{"introduced":"10.11.0"},{"last_affected":"10.11.10"},{"introduced":"11.4.0"},{"last_affected":"11.4.0"},{"introduced":"11.3.0"},{"last_affected":"11.3.1"}]}]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/3xxx/CVE-2026-3115.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-3115"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost","events":[{"introduced":"5b955468ea1ea8b56c0fb10feb258a36a767d7bb"},{"fixed":"fddd4a70bcb32eaff394a2fa5399efcd1b2ae251"},{"introduced":"ab7b138824c61fe1fe815243d7e2a914dec49c8b"},{"fixed":"005521aa79666e6960bc3302f6172b810f6bff3a"},{"introduced":"d27a2195068ddfa3ce17cf470f9739e4edb94b83"},{"fixed":"b7d4a1f1f59b645a7598181d33cfc537ea9a6c9c"},{"introduced":"2a1ac98bd3fae587927adf9340ba266c8c02018e"},{"last_affected":"2a1ac98bd3fae587927adf9340ba266c8c02018e"}],"database_specific":{"cpe":["cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*","cpe:2.3:a:mattermost:mattermost_server:11.4.0:*:*:*:*:*:*:*"],"extracted_events":[{"introduced":"10.11.0"},{"fixed":"10.11.11"},{"introduced":"11.2.0"},{"fixed":"11.2.3"},{"introduced":"11.3.0"},{"fixed":"11.3.2"},{"introduced":"11.4.0"},{"last_affected":"11.4.0"}],"source":["CPE_RANGE","CPE_STRING"]}}],"versions":["11.4.0","v11.3.1","v11.4.0-rc3","v11.4.0","mattermost-redux@11.4.0","@mattermost/types@11.4.0","@mattermost/client@11.4.0","v10.11.11-rc1","v11.3.1-rc1","v10.11.10","v11.2.2","v11.3.0-rc4","v11.3.0-rc3","v11.3.0","mattermost-redux@11.3.0","@mattermost/types@11.3.0","@mattermost/client@11.3.0","v10.11.9","v11.2.1","v11.2.1-rc1","v11.2.0","v10.11.9-rc1","v10.11.8","v10.11.7","v10.11.6","v10.11.5","v10.11.4-rc3","v10.11.4","v10.11.4-rc2","v10.11.4-rc1","v10.11.3","v10.11.2-rc2","v10.11.2","v10.11.2-rc1","v10.11.1","v10.11.1-rc1","v10.11.0-rc3","v10.11.0","mattermost-redux@10.11.0","@mattermost/types@10.11.0","@mattermost/client@10.11.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-3115.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"}]}