{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-4915", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-03-26T17:29:11.040Z", "datePublished": "2026-05-25T07:10:23.254Z", "dateUpdated": "2026-05-25T07:10:23.254Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.6.0", "status": "affected", "version": "11.6.0", "versionType": "semver"}, {"lessThanOrEqual": "11.5.3", "status": "affected", "version": "11.5.0", "versionType": "semver"}, {"lessThanOrEqual": "11.4.4", "status": "affected", "version": "11.4.0", "versionType": "semver"}, {"lessThanOrEqual": "10.11.14", "status": "affected", "version": "10.11.0", "versionType": "semver"}, {"version": "11.7.0", "status": "unaffected"}, {"version": "11.6.1", "status": "unaffected"}, {"version": "11.5.4", "status": "unaffected"}, {"version": "11.4.5", "status": "unaffected"}, {"version": "10.11.15", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "daw10"}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to filter nil elements from outgoing webhook attachment payloads before processing, which allows an authenticated user to cause a denial of service (server process termination) via a crafted webhook callback response containing a null attachment entry.. Mattermost Advisory ID: MMSA-2026-00641"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseSeverity": "MEDIUM", "baseScore": 6.5}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-754: Improper Check for Unusual or Exceptional Conditions", "cweId": "CWE-754"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00641", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, 10.11.15 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00641", "defect": ["https://mattermost.atlassian.net/browse/MM-68107"], "discovery": "EXTERNAL"}, "title": "Server panic via outgoing webhook responses", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-05-25T07:10:23.254Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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