CVE-2026-42236

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Prior to versions 1.123.32, 2.17.4, and 2.18.1, the MCP OAuth client registration endpoint accepted unauthenticated requests and stored client data without adequate resource controls. An unauthenticated remote attacker could exhaust server memory resources by sending large registration payloads, rendering the n8n instance unavailable. The MCP enable/disable toggle gates MCP access but did not restrict client registrations, meaning the endpoint is reachable regardless of whether MCP access is enabled on the instance. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1."}, {"lang": "es", "value": "n8n es una plataforma de automatizaci\u00f3n de flujos de trabajo de c\u00f3digo abierto. Antes de las versiones 1.123.32, 2.17.4 y 2.18.1, el endpoint de registro de clientes OAuth de MCP aceptaba solicitudes no autenticadas y almacenaba datos del cliente sin controles de recursos adecuados. Un atacante remoto no autenticado podr\u00eda agotar los recursos de memoria del servidor enviando grandes cargas \u00fatiles de registro, dejando la instancia de n8n no disponible. El interruptor de activaci\u00f3n/desactivaci\u00f3n de MCP restring\u00eda el acceso a MCP, pero no restring\u00eda los registros de clientes, lo que significa que el endpoint es accesible independientemente de si el acceso a MCP est\u00e1 habilitado en la instancia. Este problema ha sido parcheado en las versiones 1.123.32, 2.17.4 y 2.18.1."}], "id": "CVE-2026-42236", "lastModified": "2026-11-11T23:10:00.263", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.7, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-42236", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-05-04T19:59:10.326960Z", "version": "2.0.3"}}]}, "published": "2026-05-04T19:16:06.337", "references": [{"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/n8n-io/n8n/security/advisories/GHSA-49m9-pgww-9vq6"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

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