{"id":"CVE-2026-18223","published":"2026-10-16T08:17:12.753","lastModified":"2026-10-16T19:23:18.623","description":"Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 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","cvssScore":5,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:L/A:N","cwes":["CWE-863"],"vendors":[],"products":[],"references":[{"url":"https://mattermost.com/security-updates","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}