CVE-2025-66416

{"id": "CVE-2025-66416", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-66416", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2025-12-02T18:42:19.561436Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 8.1, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.2, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 7.6, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "PASSIVE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "modelcontextprotocol", "product": "python-sdk", "versions": [{"status": "affected", "version": "< 1.23.0"}]}]}], "published": "2025-12-02T19:15:52.520", "references": [{"url": "https://github.com/modelcontextprotocol/python-sdk/commit/d3a184119e4479ea6a63590bc41f01dc06e3fa99", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-9h52-p55h-vw2f", "tags": ["Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-1188"}]}], "descriptions": [{"lang": "en", "value": "The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.23.0, tThe Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication using FastMCP with streamable HTTP or SSE transport, and has not configured TransportSecuritySettings, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. Note that running HTTP-based MCP servers locally without authentication is not recommended per MCP security best practices. This issue does not affect servers using stdio transport. This vulnerability is fixed in 1.23.0."}, {"lang": "es", "value": "El SDK de Python de MCP, llamado 'mcp' en PyPI, es una implementaci\u00f3n en Python del Protocolo de Contexto del Modelo (MCP). Versiones anteriores a la 1.23.0, el SDK de Python del Protocolo de Contexto del Modelo (MCP) no habilita la protecci\u00f3n contra la reconfiguraci\u00f3n de DNS (DNS rebinding) por defecto para servidores basados en HTTP. Cuando un servidor MCP basado en HTTP se ejecuta en localhost sin autenticaci\u00f3n usando FastMCP con transporte HTTP o SSE en streaming, y no ha configurado TransportSecuritySettings, un sitio web malicioso podr\u00eda explotar la reconfiguraci\u00f3n de DNS (DNS rebinding) para eludir las restricciones de la pol\u00edtica de mismo origen y enviar solicitudes al servidor MCP local. Esto podr\u00eda permitir a un atacante invocar herramientas o acceder a recursos expuestos por el servidor MCP en nombre del usuario en esas circunstancias limitadas. Tenga en cuenta que ejecutar servidores MCP basados en HTTP localmente sin autenticaci\u00f3n no se recomienda seg\u00fan las mejores pr\u00e1cticas de seguridad de MCP. Este problema no afecta a los servidores que utilizan transporte stdio. Esta vulnerabilidad est\u00e1 corregida en la versi\u00f3n 1.23.0."}], "lastModified": "2026-10-18T18:10:00.100", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:lfprojects:mcp_python_sdk:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "BAEEDB0F-6542-4842-A1EB-F2A82C8D6A02", "versionEndExcluding": "1.23.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}