EUVD-2025-200273
GHSA-9h52-p55h-vw2f
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Lifecycle Timeline
4Description
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.
Analysis
CVE-2025-66416 is a security vulnerability (CVSS 8.1) that allows dns rebinding protection. High severity vulnerability requiring prompt remediation. Vendor patch is available.
Technical Context
Vulnerability type not specified by vendor. CVSS 8.1 indicates high severity.
Affected Products
['Unspecified product']
Remediation
Apply the vendor-supplied patch immediately.
Priority Score
Vendor Status
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External POC / Exploit Code
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