Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects carrying custom headers and bodies

影響: pip:mcp >= 2.0.0, < 2.2.0 → 2.2.0, pip:mcp >= 1.8.0, < 1.30.0 → 1.30.0

In affected versions, the SDK's Streamable HTTP and SSE client transports followed HTTP redirects to any host. If the configured MCP endpoint answered with a redirect to a different origin: - custom headers set on the client (for example an X-API-Key credential) were sent to that origin, and - on a 307 or 308 redirect the request body was re-sent there too. The SDK's OAuth client providers followed redirects on their own discovery, registration and token requests in the same way. A lone Authori…

Read on GitHub Advisory Database

On 10/28/2026, 06:05 AM, GitHub Advisory Database published "Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects carrying custom headers and bodies" (type: Advisory). Severity is "Medium" (medium). Related technologies: Python. CVE: CVE-2026-116685.