{"id":"CVE-2026-19603","published":"2026-10-16T07:17:12.750","lastModified":"2026-10-16T19:23:18.623","description":"Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to sanitize the active channel field returned by the user status API endpoints, which allows an authenticated user to learn the channel ID of a private channel another user is actively viewing via the status endpoints, without being a member of that channel. Mattermost Advisory ID: MMSA-2026-00765","cvssScore":4.3,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","cwes":["CWE-201"],"vendors":[],"products":[],"references":[{"url":"https://mattermost.com/security-updates","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}