CVE-2025-66416

EPSS 0.04%

Model Context Protocol (MCP) Python SDK does not enable DNS rebinding protection by default

發布日:2025/12/2修改日:2026/2/4
也稱為:GHSA-9h52-p55h-vw2fCGA-4rr5-v9cg-v92p

描述

### Description The 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. Servers created via `FastMCP()` now have DNS rebinding protection enabled by default when the `host` parameter is `127.0.0.1` or `localhost`. Users are advised to update to version `1.23.0` to receive this automatic protection. Users with custom low-level server configurations using `StreamableHTTPSessionManager` or `SseServerTransport` directly should explicitly configure `TransportSecuritySettings` when running an unauthenticated server on localhost.

受影響套件(1)

CVSS 分數

來源版本嚴重程度向量
osvCVSS 4.0—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

參考連結(4)