{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-19541", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-08-11T12:04:08.947Z", "datePublished": "2026-10-16T06:54:57.403Z", "dateUpdated": "2026-10-16T06:54:57.403Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.10", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.10.1", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"version": "11.11.0", "status": "unaffected"}, {"version": "11.9.2", "status": "unaffected"}, {"version": "11.8.6", "status": "unaffected"}, {"version": "11.7.11", "status": "unaffected"}, {"version": "11.10.2", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Juho Fors\u00e9n"}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when validating an outgoing OAuth connection, which allows an authenticated user with permission to manage outgoing OAuth connections to obtain the secret via pointing the token URL at an attacker-controlled endpoint and triggering validation.. Mattermost Advisory ID: MMSA-2026-00761"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "baseSeverity": "MEDIUM", "baseScore": 6.5}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-201: Insertion of Sensitive Information Into Sent Data", "cweId": "CWE-201"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00761", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.11.0, 11.9.2, 11.8.6, 11.7.11, 11.10.2 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00761", "defect": ["https://mattermost.atlassian.net/browse/MM-70182"], "discovery": "{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"}, "title": "Outgoing OAuth connection client secret exposure during connection validation", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-10-16T06:54:57.403Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.10", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.10.1", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"status": "unaffected", "version": "11.11.0"}, {"status": "unaffected", "version": "11.9.2"}, {"status": "unaffected", "version": "11.8.6"}, {"status": "unaffected", "version": "11.7.11"}, {"status": "unaffected", "version": "11.10.2"}]}], "source": "responsibledisclosure@mattermost.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when validating an outgoing OAuth connection, which allows an authenticated user with permission to manage outgoing OAuth connections to obtain the secret via pointing the token URL at an attacker-controlled endpoint and triggering validation.. Mattermost Advisory ID: MMSA-2026-00761"}], "id": "CVE-2026-19541", "lastModified": "2026-10-16T07:17:12.520", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}, "published": "2026-10-16T07:17:12.520", "references": [{"source": "responsibledisclosure@mattermost.com", "url": "https://mattermost.com/security-updates"}], "sourceIdentifier": "responsibledisclosure@mattermost.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-201"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

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