{"id":"CVE-2026-2458","aliases":["GHSA-679f-wmrg-qf57","GO-2026-4729"],"url":"https://o3.security/vulnerability/CVE-2026-2458","summary":"Unauthorized channel enumeration in private teams after member removal","details":"Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly validate team membership when searching channels which allows a removed team member to enumerate all public channels within a private team via the channel search API endpoint.. Mattermost Advisory ID: MMSA-2025-00568","published":"2026-03-16T11:27:49.310Z","modified":"2026-07-31T18:30:34.056231735Z","cvss":{"score":4.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/mattermost/mattermost/server/v8","fixedVersion":"8.0.0-20260113182106-a18b80ba4c32"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"5.3.2-0.20260113182106-a18b80ba4c32"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"10.11.11"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.2.3"},{"ecosystem":"Go","name":"github.com/mattermost/mattermost-server","fixedVersion":"11.3.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2458.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-2458"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-31T18:30:34.056231735Z"}}