CVE-2026-40576

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{"affected": [{"affectedData": [{"product": "excel-mcp-server", "vendor": "haris-musa", "versions": [{"status": "affected", "version": "< 0.1.8"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "excel-mcp-server is a Model Context Protocol server for Excel file manipulation. A path traversal vulnerability exists in excel-mcp-server versions up to and including 0.1.7. When running in SSE or Streamable-HTTP transport mode (the documented way to use this server remotely), an unauthenticated attacker on the network can read, write, and overwrite arbitrary files on the host filesystem by supplying crafted filepath arguments to any of the 25 exposed MCP tool handlers. The server is intended to confine file operations to a directory set by the EXCEL_FILES_PATH environment variable. The function responsible for enforcing this boundary \u2014 get_excel_path() \u2014 fails to do so due to two independent flaws: it passes absolute paths through without any check, and it joins relative paths without resolving or validating the result. Combined with zero authentication on the default network-facing transport and a default bind address of 0.0.0.0 (all interfaces), this allows trivial remote exploitation. This vulnerability is fixed in 0.1.8."}, {"lang": "es", "value": "excel-mcp-server es un servidor de Protocolo de Contexto de Modelo para la manipulaci\u00f3n de archivos de Excel. Existe una vulnerabilidad de salto de ruta en las versiones de excel-mcp-server hasta la 0.1.7 inclusive. Cuando se ejecuta en modo de transporte SSE o Streamable-HTTP (la forma documentada de usar este servidor remotamente), un atacante no autenticado en la red puede leer, escribir y sobrescribir archivos arbitrarios en el sistema de archivos del host al proporcionar argumentos de ruta de archivo manipulados a cualquiera de los 25 manejadores de herramientas MCP expuestos. El servidor est\u00e1 dise\u00f1ado para confinar las operaciones de archivo a un directorio establecido por la variable de entorno EXCEL_FILES_PATH. La funci\u00f3n responsable de hacer cumplir este l\u00edmite - get_excel_path() - no lo hace debido a dos fallas independientes: pasa rutas absolutas sin ninguna verificaci\u00f3n y une rutas relativas sin resolver o validar el resultado. Combinado con autenticaci\u00f3n nula en el transporte predeterminado orientado a la red y una direcci\u00f3n de enlace predeterminada de 0.0.0.0 (todas las interfaces), esto permite una explotaci\u00f3n remota trivial. Esta vulnerabilidad est\u00e1 corregida en la 0.1.8."}], "id": "CVE-2026-40576", "lastModified": "2026-10-26T21:10:00.170", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.4, "baseSeverity": "CRITICAL", "confidentialityImpact": "LOW", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.5, "source": "security-advisories@github.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.4, "baseSeverity": "CRITICAL", "confidentialityImpact": "LOW", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.5, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-40576", "options": [{"exploitation": "poc"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-04-21T16:49:44.652947Z", "version": "2.0.3"}}]}, "published": "2026-04-21T17:16:55.870", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/haris-musa/excel-mcp-server/security/advisories/GHSA-j98m-w3xp-9f56"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/haris-musa/excel-mcp-server/security/advisories/GHSA-j98m-w3xp-9f56"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-22"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,0.1.8)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "cna", "scores": [{"score": 100.0, "source": "cna"}]}, "original": {"product": "excel-mcp-server", "source": "cna", "vendor": "haris-musa"}, "product": "excel-mcp-server", "vendor": "haris-musa"}], "analysis": {"en": {"generated_at": "2026-04-21T22:38:42.635019+00:00", "value": {"mitigation_remediation": ["Upgrade excel\u2011mcp\u2011server to version 0.1.8 or later, where the path traversal checks are corrected.", "If an upgrade is not immediately possible, restrict network access to the server by firewall or binding the service to localhost to prevent external connections.", "Set the EXCEL_FILES_PATH to a non\u2011privileged, secure directory and verify that the server does not use absolute paths; consider disabling SSE or Streamable-HTTP transport mode if authentication is required."], "summary": {"action": "Immediate Patch", "impact": "Remote File Manipulation"}, "threat_synthesis": {"affected_systems": "The affected product is haris\u2011musa's excel\u2011mcp\u2011server, with versions up to and including 0.1.7 vulnerable. The vulnerability is relevant when the server runs in SSE or Streamable\u2011HTTP transport mode, which are the documented methods for remote use. The server relies on the EXCEL_FILES_PATH environment variable to limit file operations, but this checkpoint is bypassed by the flaw.", "description_and_impact": "The vulnerability is a path traversal flaw (CWE\u201122) that permits an unauthenticated attacker to supply crafted file paths to any of the 25 exposed MCP tool handlers. In SSE or Streamable\u2011HTTP transport mode the server is intended to confine file operations to the directory set by the EXCEL_FILES_PATH environment variable, but the enforcement function fails to check absolute paths and does not resolve relative paths, allowing the attacker to read, write, or overwrite any file on the host filesystem. This could lead to unauthorized data disclosure, tampering, or potentially execution of malicious code if files are written where they can be executed.", "risk_and_exploitability": "The CVSS score is 9.4, indicating high severity, and the EPSS score is not available; it is not listed in the CISA KEV catalog. The default configuration binds to 0.0.0.0 (all interfaces) with no authentication, giving an attacker trivial remote access to the vulnerability. Attack conditions require only network connectivity to the exposed transport, making exploitation straightforward."}}}}, "created": "2026-04-21T22:45:16.058033+00:00", "updated": "2026-04-22T11:46:09.829367+00:00", "vendors": ["haris-musa", "haris-musa$PRODUCT$excel-mcp-server"]}