{"id":"CVE-2026-19603","revision":"2442cff55b84499dbd83326374d6a18d","records":[{"revision":"2442cff55b84499dbd83326374d6a18d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-19603","aliases":[],"title":"Private channel ID disclosure via user status endpoints","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","state":0,"publishedAt":"2026-10-16T07:02:38.486+00:00","modifiedAt":"2026-10-16T11:59:09.985+00:00","affected":[{"ecosystem":"Vendor product","name":"Mattermost","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"defaultStatus\": \"unaffected\",\n                    \"product\": \"Mattermost\",\n                    \"vendor\": \"Mattermost\",\n                    \"versions\": [\n                        {\n                            \"lessThanOrEqual\": \"11.9.1\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.9.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThanOrEqual\": \"11.8.5\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.8.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThanOrEqual\": \"11.7.10\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.7.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"lessThanOrEqual\": \"11.10.1\",\n                            \"status\": \"affected\",\n                            \"version\": \"11.10.0\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"11.11.0\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.9.2\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.8.6\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.7.11\",\n                            \"status\": \"unaffected\"\n                        },\n                        {\n                            \"version\": \"11.10.2\",\n                            \"status\": \"unaffected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","score":4.3,"severity":"MEDIUM"}],"references":["https://mattermost.com/security-updates"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-19603","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-19603","identifiers":["CVE-2026-19603"]},"retained":false,"historicalAffected":[]}],"coverage":[]}