{"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 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"}}, "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"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-20796", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-02-13T17:01:37.056493Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-02-13T17:01:43.299Z"}}], "cna": {"title": "Time-of-check time-of-use vulnerability in common teams API", "source": {"defect": ["https://mattermost.atlassian.net/browse/MM-66423"], "advisory": "MMSA-2025-00549", "discovery": "{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"}, "credits": [{"lang": "en", "type": "finder", "value": "Juho Fors\u00e9n"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 3.1, "attackVector": "NETWORK", "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "LOW"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "Mattermost", "product": "Mattermost", "versions": [{"status": "affected", "version": "10.11.0", "versionType": "semver", "lessThanOrEqual": "10.11.9"}, {"status": "unaffected", "version": "11.3.0"}, {"status": "unaffected", "version": "10.11.10"}], "defaultStatus": "unaffected"}], "solutions": [{"lang": "en", "value": "Update Mattermost to versions 11.3.0, 10.11.10 or higher."}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2025-00549", "tags": ["vendor-advisory"]}], "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"}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-367", "description": "CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition"}]}], "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-02-13T10:30:03.445Z"}}}, "cveMetadata": {"cveId": "CVE-2026-20796", "state": "PUBLISHED", "dateUpdated": "2026-02-13T17:02:25.985Z", "dateReserved": "2026-01-15T11:34:00.225Z", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "datePublished": "2026-02-13T10:30:03.445Z", "assignerShortName": "Mattermost"}, "dataVersion": "5.2"}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "92B0F8BD-06A1-4B39-95C5-4FB5A195F1C4", "versionEndExcluding": "10.11.10", "versionStartIncluding": "10.11.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "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"}, {"lang": "es", "value": "Las versiones de Mattermost 10.11.x &lt;= 10.11.9 no validan correctamente la membres\u00eda del canal en el momento de la recuperaci\u00f3n de datos, lo que permite a un usuario desactivado conocer nombres de equipos a los que no deber\u00eda tener acceso a trav\u00e9s de una condici\u00f3n de carrera en el endpoint de la API /common_teams. ID de Aviso de Mattermost: MMSA-2025-00549"}], "id": "CVE-2026-20796", "lastModified": "2026-02-23T15:53:11.073", "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", "tags": ["Vendor Advisory"], "url": "https://mattermost.com/security-updates"}], "sourceIdentifier": "responsibledisclosure@mattermost.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-367"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

{}

{"created": "2026-02-13T21:28:43.226353+00:00", "updated": "2026-02-13T21:28:43.226421+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost"]}