{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-2456", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-02-13T11:02:52.828Z", "datePublished": "2026-03-16T11:06:44.920Z", "dateUpdated": "2026-03-16T13:49:58.650Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.3.0", "status": "affected", "version": "11.3.0", "versionType": "semver"}, {"lessThanOrEqual": "11.2.2", "status": "affected", "version": "11.2.0", "versionType": "semver"}, {"lessThanOrEqual": "10.11.10", "status": "affected", "version": "10.11.0", "versionType": "semver"}, {"version": "11.4.0", "status": "unaffected"}, {"version": "11.3.1", "status": "unaffected"}, {"version": "11.2.3", "status": "unaffected"}, {"version": "10.11.11", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "Daniel Espino Garcia"}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseSeverity": "MEDIUM", "baseScore": 5.3}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-789: Memory Allocation with Excessive Size Value", "cweId": "CWE-789"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00571", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.4.0, 11.3.1, 11.2.3, 10.11.11 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00571", "defect": ["https://mattermost.atlassian.net/browse/MM-67073"], "discovery": "{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"}, "title": "Denial of Service via Unbounded Memory Allocation in Integration Actions", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-03-16T11:06:44.920Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-2456", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-16T13:43:01.562781Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-16T13:49:58.650Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-2456", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-16T13:43:01.562781Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-16T13:44:23.990Z"}}], "cna": {"title": "Denial of Service via Unbounded Memory Allocation in Integration Actions", "source": {"defect": ["https://mattermost.atlassian.net/browse/MM-67073"], "advisory": "MMSA-2026-00571", "discovery": "{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"}, "credits": [{"lang": "en", "type": "finder", "value": "Daniel Espino Garcia"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "REQUIRED", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "Mattermost", "product": "Mattermost", "versions": [{"status": "affected", "version": "11.3.0", "versionType": "semver", "lessThanOrEqual": "11.3.0"}, {"status": "affected", "version": "11.2.0", "versionType": "semver", "lessThanOrEqual": "11.2.2"}, {"status": "affected", "version": "10.11.0", "versionType": "semver", "lessThanOrEqual": "10.11.10"}, {"status": "unaffected", "version": "11.4.0"}, {"status": "unaffected", "version": "11.3.1"}, {"status": "unaffected", "version": "11.2.3"}, {"status": "unaffected", "version": "10.11.11"}], "defaultStatus": "unaffected"}], "solutions": [{"lang": "en", "value": "Update Mattermost to versions 11.4.0, 11.3.1, 11.2.3, 10.11.11 or higher."}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00571", "tags": ["vendor-advisory"]}], "x_generator": {"engine": "cvelib 1.8.0"}, "descriptions": [{"lang": "en", "value": "Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571"}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-789", "description": "CWE-789: Memory Allocation with Excessive Size Value"}]}], "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-03-16T11:06:44.920Z"}}}, "cveMetadata": {"cveId": "CVE-2026-2456", "state": "PUBLISHED", "dateUpdated": "2026-03-16T13:49:58.650Z", "dateReserved": "2026-02-13T11:02:52.828Z", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "datePublished": "2026-03-16T11:06:44.920Z", "assignerShortName": "Mattermost"}, "dataVersion": "5.2"}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "B6E5F368-358C-429B-8F04-3C8DF4A71A91", "versionEndExcluding": "10.11.11", "versionStartIncluding": "10.11.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "7F64C167-943D-4F3F-9374-BCC8DECB3881", "versionEndExcluding": "11.2.3", "versionStartIncluding": "11.2.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "945A6E29-209F-4992-8692-BEF63DCB6B98", "versionEndExcluding": "11.3.1", "versionStartIncluding": "11.3.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571"}, {"lang": "es", "value": "Versiones de Mattermost 11.3.x &lt;= 11.3.0, 11.2.x &lt;= 11.2.2, 10.11.x &lt;= 10.11.10 Mattermost no limita el tama\u00f1o de las respuestas de los puntos finales de acci\u00f3n de integraci\u00f3n, lo que permite a un atacante autenticado causar el agotamiento de la memoria del servidor y denegaci\u00f3n de servicio a trav\u00e9s de un servidor de integraci\u00f3n malicioso que devuelve una respuesta arbitrariamente grande cuando un usuario hace clic en un bot\u00f3n de mensaje interactivo. ID de Aviso de Mattermost: MMSA-2026-00571"}], "id": "CVE-2026-2456", "lastModified": "2026-03-18T18:27:57.000", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 3.6, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 5.7, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.1, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2026-03-16T14:19:29.190", "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-789"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.3.0,11.3.0]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.2.0,11.2.2]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[10.11.0,10.11.10]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[11.4.0,11.4.0]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[11.3.1,11.3.1]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[11.2.3,11.2.3]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[10.11.11,10.11.11]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Mattermost", "source": "cna", "vendor": "Mattermost"}, "product": "mattermost", "vendor": "mattermost"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,*]"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "product": "server", "vendor": "mattermost"}], "analysis": {"en": {"generated_at": "2026-03-18T19:55:04.293835+00:00", "value": {"mitigation_remediation": ["Upgrade Mattermost to a fixed version (11.4.0, 11.3.1, 11.2.3, 10.11.11 or later).", "If an upgrade cannot be applied immediately, restrict integration responses to a safe size and monitor server memory for abnormal usage."], "summary": {"action": "Apply Patch", "impact": "Denial of Service"}, "threat_synthesis": {"affected_systems": "The affected product is Mattermost Server. Vulnerable releases are 11.3.x through 11.3.0, 11.2.x through 11.2.2, and 10.11.x through 10.11.10. The vendor recommends upgrading to fixed versions 11.4.0, 11.3.1, 11.2.3, or 10.11.11 or later (vendor solution).", "description_and_impact": "Mattermost fails to limit the size of responses from integration action endpoints, as stated in the vendor description: \"Mattermost fails to limit the size of responses from integration action endpoints\", allowing an authenticated attacker who controls a malicious integration server to trigger unbounded memory allocation. When a user clicks an interactive message button, the server processes an arbitrarily large payload and exhausts its memory, resulting in a denial of service. This weakness is identified as CWE-789, Uncontrolled Resource Consumption (CVE description).", "risk_and_exploitability": "The CVSS score of 5.3 indicates moderate severity (scores). The EPSS score is less than 1%, reflecting a low likelihood of exploitation (scores). This vulnerability is not listed in the CISA KEV catalog. Exploitation requires an authenticated Mattermost user with access to an integration endpoint; when triggered, the server may become unavailable until memory is reclaimed or the service is restarted. Overall risk is moderate, but the probability remains low due to prerequisites."}}}}, "created": "2026-03-24T10:45:00.454040+00:00", "updated": "2026-03-30T07:02:49.047014+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost", "mattermost$PRODUCT$server"]}