{"schema":"threatline.record/2","record":{"id":"CVE-2026-18799","aliases":[],"summary":"Mattermost Server fails to restrict Slack import account binding, allowing team admins to forge posts as existing users","details":"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","categories":["Applications & CMS"],"product":"Mattermost","vendor":"Mattermost","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-18799","source_modified_at":"2026-10-16T11:28:45.200Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"Mattermost","vendor":"Mattermost","versions":[{"lessThanOrEqual":"11.10.0","status":"affected","version":"11.10.0","versionType":"semver"},{"lessThanOrEqual":"11.7.9","status":"affected","version":"11.7.0","versionType":"semver"},{"lessThanOrEqual":"11.9.1","status":"affected","version":"11.9.0","versionType":"semver"},{"lessThanOrEqual":"11.8.5","status":"affected","version":"11.8.0","versionType":"semver"},{"version":"11.11.0","status":"unaffected"},{"version":"11.10.1","status":"unaffected"},{"version":"11.7.10","status":"unaffected"},{"version":"11.9.2","status":"unaffected"},{"version":"11.8.6","status":"unaffected"}],"defaultStatus":"unaffected"}],"fixed_versions":[],"cvss":4.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00152,"percentile":0.04017,"score_date":"2026-10-23"},"published_at":"2026-10-16T07:16:19.062Z","modified_at":"2026-10-16T11:28:45.200Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-18799","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-16T11:28:45.200Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-18799","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":"2026-10-16T11:28:31.537040Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-16T11:28:45.200Z","content_hash":"7d597d8092880f64e7765adf330d85e547cf5e344be6b23f18128f2398928f44"}}