{"schema":"threatline.record/2","record":{"id":"CVE-2026-19603","aliases":[],"summary":"Private channel ID disclosure via user status endpoints","details":"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","categories":["Applications & CMS"],"product":"Mattermost","vendor":"Mattermost","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-19603","source_modified_at":"2026-10-16T11:59:09.985Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"Mattermost","vendor":"Mattermost","versions":[{"lessThanOrEqual":"11.9.1","status":"affected","version":"11.9.0","versionType":"semver"},{"lessThanOrEqual":"11.8.5","status":"affected","version":"11.8.0","versionType":"semver"},{"lessThanOrEqual":"11.7.10","status":"affected","version":"11.7.0","versionType":"semver"},{"lessThanOrEqual":"11.10.1","status":"affected","version":"11.10.0","versionType":"semver"},{"version":"11.11.0","status":"unaffected"},{"version":"11.9.2","status":"unaffected"},{"version":"11.8.6","status":"unaffected"},{"version":"11.7.11","status":"unaffected"},{"version":"11.10.2","status":"unaffected"}],"defaultStatus":"unaffected"}],"fixed_versions":[],"cvss":4.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00176,"percentile":0.06808,"score_date":"2026-10-23"},"published_at":"2026-10-16T07:02:38.486Z","modified_at":"2026-10-16T11:59:09.985Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-19603","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-16T11:59:09.985Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-19603","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://mattermost.com/security-updates","tags":["vendor-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-16T11:58:53.325388Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-16T11:59:09.985Z","content_hash":"dec87416a9d2c900a1e27de7c55029c3163acf9ba1cefb3f2026041afae8cd56"}}