Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2025-66416— DNS Rebinding Protection Disabled by Default in Model Context Protocol Python SDK for Servers Running on Localhost

Quick assessment

Affected
modelcontextprotocol python-sdk
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Model Context Protocol Python SDK是Model Context Protocol开源的一个用于模型上下文协议服务器和客户端的开发工具。 Model Context Protocol Python SDK 1.23.0之前版本存在安全漏洞，该漏洞源于默认未启用DNS重绑定保护，可能导致绕过同源策略限制。

AI Predicted 5.3 Difficulty: Easy EPSS 0.51% · P42

Possible ATT&CK Techniques 1 AI

T1557 · Adversary-in-the-Middle
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2025-66416

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
DNS Rebinding Protection Disabled by Default in Model Context Protocol Python SDK for Servers Running on Localhost
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
不安全的默认资源初始化
Source: CVE Program / CVE List V5
Vulnerability Title
Model Context Protocol Python SDK 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Model Context Protocol Python SDK是Model Context Protocol开源的一个用于模型上下文协议服务器和客户端的开发工具。 Model Context Protocol Python SDK 1.23.0之前版本存在安全漏洞，该漏洞源于默认未启用DNS重绑定保护，可能导致绕过同源策略限制。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
modelcontextprotocol python-sdk < 1.23.0 -

II. Public POCs for CVE-2025-66416

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2025-66416

请登录查看更多情报信息。

IV. Related Vulnerabilities

Same product: python-sdk
Same vendor: modelcontextprotocol
Same weakness: CWE-1188

V. Comments for CVE-2025-66416

No comments yet

Leave a comment