CVE-2025-53365: Modelcontextprotocol Python-SDK

High severity, CVSS 8.7. EPSS: 0.4% chance of exploitation in the next 30 days.

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.10.0, if a client deliberately triggers an exception after establishing a streamable HTTP session, this can lead to an uncaught ClosedResourceError on the server side, causing the server to crash and requiring a restart to restore service. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.10.0 contains a patch for the issue.

Affected products

• Modelcontextprotocol Python-SDK: before 1.10.0 (fixed in 1.10.0)

Published 2025-07-04. Last modified 2026-06-17.