{"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": "2026-02-13T10:30:03.445Z"}, "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 Fors\u00e9n"}], "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"}}}}

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{"cveTags": [], "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"}], "id": "CVE-2026-20796", "lastModified": "2026-02-13T11:16:10.280", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 3.1, "baseSeverity": "LOW", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 1.4, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}, "published": "2026-02-13T11:16:10.280", "references": [{"source": "responsibledisclosure@mattermost.com", "url": "https://mattermost.com/security-updates"}], "sourceIdentifier": "responsibledisclosure@mattermost.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-367"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

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