{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-20796","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","state":"PUBLISHED","assignerShortName":"Mattermost","dateReserved":"2026-01-15T11:34:00.225Z","datePublished":"2026-02-13T10:30:03.445Z","dateUpdated":"2026-02-13T17:02:25.985Z"},"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Mattermost","vendor":"Mattermost","versions":[{"lessThanOrEqual":"10.11.9","status":"affected","version":"10.11.0","versionType":"semver"},{"version":"11.3.0","status":"unaffected"},{"version":"10.11.10","status":"unaffected"}]}],"credits":[{"lang":"en","type":"finder","value":"Juho Forsén"}],"descriptions":[{"lang":"en","value":"Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549"}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"NONE","availabilityImpact":"NONE","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N","baseSeverity":"LOW","baseScore":3.1},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"lang":"en","type":"CWE","description":"CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition","cweId":"CWE-367"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2025-00549","tags":["vendor-advisory"]}],"solutions":[{"value":"Update Mattermost to versions 11.3.0, 10.11.10 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2025-00549","defect":["https://mattermost.atlassian.net/browse/MM-66423"],"discovery":"{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"},"title":"Time-of-check time-of-use vulnerability in common teams API","providerMetadata":{"orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","shortName":"Mattermost","dateUpdated":"2026-02-13T10:30:03.445Z"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-02-13T17:01:37.056493Z","id":"CVE-2026-20796","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-02-13T17:02:25.985Z"}}]}}