{"id":"CVE-2026-18799","published":"2026-10-16T08:17:13.073","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 restrict Slack import account binding to system administrator-initiated imports which allows an authenticated attacker with team admin privileges to force-add existing Mattermost users to their team and forge posts attributed to those users' identities via a crafted Slack export containing target users' email addresses.. Mattermost Advisory ID: MMSA-2026-00757","cvssScore":4.3,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","cwes":["CWE-862"],"vendors":[],"products":[],"references":[{"url":"https://mattermost.com/security-updates","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}