CVE-2026-18795

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-18795", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-08-04T09:13:11.334Z", "datePublished": "2026-10-16T07:01:22.549Z", "dateUpdated": "2026-10-16T11:59:42.771Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.10.0", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.9", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"version": "11.11.0", "status": "unaffected"}, {"version": "11.10.1", "status": "unaffected"}, {"version": "11.7.10", "status": "unaffected"}, {"version": "11.9.2", "status": "unaffected"}, {"version": "11.8.6", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Harshil Sharma"}], "descriptions": [{"lang": "en", "value": "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 enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "LOW", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L", "baseSeverity": "MEDIUM", "baseScore": 6.4}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-862: Missing Authorization", "cweId": "CWE-862"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00756", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00756", "defect": ["https://mattermost.atlassian.net/browse/MM-70098"], "discovery": "EXTERNAL"}, "title": "Missing server side validation allowed user to quarantine a DM and GM post", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-10-16T07:01:22.549Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-10-16T11:59:31.276508Z", "id": "CVE-2026-18795", "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": "2026-10-16T11:59:42.771Z"}}]}}

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-18795", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-08-04T09:13:11.334Z", "datePublished": "2026-10-16T07:01:22.549Z", "dateUpdated": "2026-10-16T11:59:42.771Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.10.0", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.9", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"version": "11.11.0", "status": "unaffected"}, {"version": "11.10.1", "status": "unaffected"}, {"version": "11.7.10", "status": "unaffected"}, {"version": "11.9.2", "status": "unaffected"}, {"version": "11.8.6", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Harshil Sharma"}], "descriptions": [{"lang": "en", "value": "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 enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "availabilityImpact": "LOW", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L", "baseSeverity": "MEDIUM", "baseScore": 6.4}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-862: Missing Authorization", "cweId": "CWE-862"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00756", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00756", "defect": ["https://mattermost.atlassian.net/browse/MM-70098"], "discovery": "EXTERNAL"}, "title": "Missing server side validation allowed user to quarantine a DM and GM post", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-10-16T07:01:22.549Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-18795", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-10-16T11:59:31.276508Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T11:59:37.292Z"}}]}}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.10.0", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.9", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"status": "unaffected", "version": "11.11.0"}, {"status": "unaffected", "version": "11.10.1"}, {"status": "unaffected", "version": "11.7.10"}, {"status": "unaffected", "version": "11.9.2"}, {"status": "unaffected", "version": "11.8.6"}]}], "source": "responsibledisclosure@mattermost.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "0D5A7979-C6DD-4EEA-B7C4-60C425EAD2C3", "versionEndExcluding": "11.7.10", "versionStartIncluding": "11.7.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "864932C7-FD92-48AC-8789-DF73D5CA9AAF", "versionEndExcluding": "11.8.6", "versionStartIncluding": "11.8.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "2F937268-2154-4B45-B9E0-8B3451070CD0", "versionEndExcluding": "11.9.2", "versionStartIncluding": "11.9.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:11.10.0:*:*:*:*:*:*:*", "matchCriteriaId": "C945CD83-FCEB-439D-8F18-02213CE7E7BF", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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 enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756"}], "id": "CVE-2026-18795", "lastModified": "2026-10-29T18:08:37.923", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 6.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 4.7, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-18795", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T11:59:31.276508Z", "version": "2.0.3"}}]}, "published": "2026-10-16T07:17:12.407", "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-862"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "11.10.0"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.7.0,11.7.9]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.9.0,11.9.1]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.8.0,11.8.5]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.11.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.10.1"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.7.10"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.9.2"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.8.6"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Mattermost", "source": "cna", "vendor": "Mattermost"}, "product": "mattermost", "vendor": "mattermost"}], "created": "2026-10-16T13:23:47.970079+00:00", "updated": "2026-10-17T16:30:07.729708+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost"]}