modelcontextprotocol typescript-sdk up to 1.23.x insecure default initialization of resource

Summaryinfo

A vulnerability was found in modelcontextprotocol typescript-sdk up to 1.23.x. It has been declared as problematic. Affected is an unknown function. Executing a manipulation can lead to insecure default initialization of resource. This vulnerability is tracked as CVE-2025-66414. The attack is restricted to local execution. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in modelcontextprotocol typescript-sdk up to 1.23.x and classified as problematic. This vulnerability affects some unknown processing. The manipulation with an unknown input leads to a insecure default initialization of resource vulnerability. The CWE definition for the vulnerability is CWE-1188. The product initializes or sets a resource with a default that is intended to be changed by the administrator, but the default is not secure. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2025-66414 since 11/29/2025. The exploitation appears to be easy. Local access is required to approach this attack. The technical details are unknown and an exploit is not available.

Upgrading to version 1.24.0 eliminates this vulnerability.

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Productinfo

Vendor

• modelcontextprotocol

Name

• typescript-sdk

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23

Website

• Product: https://github.com/modelcontextprotocol/typescript-sdk/

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