{"schemaVersion":3,"id":"CVE-2026-18256","aliases":[],"status":"published","duplicateOf":null,"title":null,"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 properly restrict private teams from public team search results, which allows an authenticated user without permission to list private teams to disclose the ID, name, and display name of private teams via a modified team search request. Mattermost Advisory ID: MMSA-2026-00748","dates":{"published":"2026-10-16T07:13:43.684Z","modified":"2026-10-16T11:58:08.912Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":4.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":4.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":4.3,"severity":"medium","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00162,"percentile":0.04955,"severity":"low","asOf":"2026-10-20T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-16T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00162,"percentile":0.04955}],"last30":[{"date":"2026-10-16T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00162,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00162,"percentile":0.04955}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-863","name":"Incorrect Authorization","description":"The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.","type":"weakness","status":"Incomplete","abstraction":"Class","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/863.html"}],"affected":[{"vendor":"mattermost","product":"mattermost","name":"Mattermost","label":"mattermost","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"11.10.0","noFixRecorded":false,"fixedIn":null},{"text":"≥ 11.7.0, ≤ 11.7.9","noFixRecorded":false,"fixedIn":null},{"text":"≥ 11.9.0, ≤ 11.9.1","noFixRecorded":false,"fixedIn":null},{"text":"≥ 11.8.0, ≤ 11.8.5","noFixRecorded":false,"fixedIn":null}],"versionsText":"11.10.0 | ≥ 11.7.0, ≤ 11.7.9 | ≥ 11.9.0, ≤ 11.9.1 | ≥ 11.8.0, ≤ 11.8.5","eol":null,"hubHref":"/vendor/mattermost/mattermost"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://mattermost.com/security-updates","label":"mattermost.com/security-updates","hostname":"mattermost.com","tags":["Vendor Advisory"]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-16T07:13:43.684Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-16T11:58:08.912Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":17,"level":"low","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-21T10:57:26.073Z","stale":false,"partial":false}}