{"id":"CVE-2026-18223","aliases":["EUVD-2026-102748","GHSA-j732-3464-9jvm"],"status":"published","title":"Mattermost invitation tokens not bound to invited email address allowing unauthorized team and private channel access","description":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747","severity":{"version":"3.1","score":5,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00161,"percentile":0.05303,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2026-10-16T07:12:39Z","modified":"2026-10-31T02:49:01Z","products":[{"vendor":"mattermost","product":"mattermost"},{"vendor":"mattermost","product":"mattermost_server"}],"references":[{"url":"https://mattermost.com/security-updates","tags":["vendor-advisory","Vendor Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-18223","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-j732-3464-9jvm"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/18xxx/CVE-2026-18223.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-18223","title":"Mattermost invitation tokens not bound to invited email address allowing unauthorized team and private channel access","description":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747","status":"published","published":"2026-10-16T07:12:39.911Z","modified":"2026-10-16T14:16:33.994Z","cvss":[{"version":"3.1","score":5,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:20:12.60856Z"}],"euvd":[{"id":"EUVD-2026-102748","description":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747","status":"published","published":"2026-10-16T07:12:39Z","modified":"2026-10-16T14:16:33Z","cvss":[{"version":"3.1","score":5,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T17:00:06.126239Z"}],"ghsa":[{"id":"GHSA-j732-3464-9jvm","title":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail...","description":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747","status":"published","published":"2026-10-16T09:30:29Z","modified":"2026-10-16T09:30:35Z","cvss":[{"version":"3.1","score":5,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:13:51.12467Z"}],"nvd":[{"id":"CVE-2026-18223","description":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747","status":"published","published":"2026-10-16T08:17:12.753Z","modified":"2026-10-29T18:08:29.327Z","cvss":[{"version":"3.1","score":5,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T14:12:59.751798Z"}],"osv":[{"id":"CVE-2026-18223","title":"Mattermost invitation tokens not bound to invited email address allowing unauthorized team and private channel access","description":"Mattermost versions 11.10.x \u003c= 11.10.0, 11.7.x \u003c= 11.7.9, 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5 fail to validate the invited recipient's email address when redeeming team and guest invitation tokens, which allows an authenticated attacker to join a team or gain unauthorized access to private channels via a forwarded or leaked invitation link.. Mattermost Advisory ID: MMSA-2026-00747","status":"published","published":"2026-10-16T07:12:39.911Z","modified":"2026-10-31T02:49:01.025215812Z","cvss":[{"version":"3.1","score":5,"vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-02T15:44:58.024074Z"}]}}