CVE-2025-66414: @modelcontextprotocol/sdk Model Context Protocol (MCP) TypeScript Vulnerability
HIGHCVE-2025-66414 is a HIGH model context protocol (mcp) typescript vulnerability (CWE-1188: Initialization of a Resource with an Insecure Default) affecting @modelcontextprotocol/sdk libraries in the npm ecosystem. The issue involves model context protocol (mcp) typescript sdk does not enable dns rebinding protection by default. Remediation is available by upgrading affected packages to version 1.24.0.
CVE-2025-66414 at a Glance
How to Fix CVE-2025-66414
To remediate this vulnerability, upgrade all affected @modelcontextprotocol/sdk dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
npm install @modelcontextprotocol/sdk@1.24.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
npm ls @modelcontextprotocol/sdkHow to Check if You Are Affected
To determine whether your Node.js application is affected by CVE-2025-66414, inspect your project dependencies using npm:
npm ls @modelcontextprotocol/sdkAnalyze the terminal output to locate any version of @modelcontextprotocol/sdk in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.24.0), your application is affected.
Note: The npm ls @modelcontextprotocol/sdk command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-1188: Initialization of a Resource with an Insecure Default, where the product initializes or sets a resource with a default that is intended to be changed by the product's installer, administrator, or maintainer, but the default is not secure. In @modelcontextprotocol/sdk, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2025-66414 Affected @modelcontextprotocol/sdk Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
@modelcontextprotocol/sdk
|
npm |
< 1.24.0
|
1.24.0
|
References
Frequently Asked Questions
What is CVE-2025-66414?
Which @modelcontextprotocol/sdk versions are affected?
What version fixes CVE-2025-66414?
Is @modelcontextprotocol/sdk affected?
What CWE is associated with CVE-2025-66414?
How can I check npm dependencies for CVE-2025-66414?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-w48q-cv73-mx4w",
"modified" : "2025-12-02T21:43:49Z",
"published" : "2025-12-02T16:51:57Z",
"aliases" : [ "CVE-2025-66414" ],
"summary" : "Model Context Protocol (MCP) TypeScript SDK does not enable DNS rebinding protection by default",
"details" : "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.\n\nNote 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.\n\nServers created via `createMcpExpressApp()` now have this protection enabled by default when binding to localhost. Users with custom Express configurations are advised to update to version `1.24.0` and apply the exported `hostHeaderValidation()` middleware when running an unauthenticated server on localhost.",
"severity" : [ {
"type" : "CVSS_V4",
"score" : "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"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "npm",
"name" : "@modelcontextprotocol/sdk"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.24.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-w48q-cv73-mx4w"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-66414"
}, {
"type" : "WEB",
"url" : "https://github.com/modelcontextprotocol/typescript-sdk/pull/1205"
}, {
"type" : "WEB",
"url" : "https://github.com/modelcontextprotocol/typescript-sdk/commit/09623e2aa5044f9e9da62c73d820a8250b9d97ed"
}, {
"type" : "WEB",
"url" : "https://github.com/modelcontextprotocol/typescript-sdk/commit/608360047dc6899f1cf4f0226eb62fe7b11b3898"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/modelcontextprotocol/typescript-sdk"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-1188", "CWE-350" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2025-12-02T16:51:57Z",
"nvd_published_at" : "2025-12-02T19:15:52Z"
}
}