Vulnerability Description
The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.9.4, a validation error in the MCP SDK can cause an unhandled exception when processing malformed requests, resulting in service unavailability (500 errors) until manually restarted. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.9.4 contains a patch for the issue.
Related Weaknesses (CWE)
References
- https://github.com/modelcontextprotocol/python-sdk/commit/29c69e6a47d0104d0afcea
- https://github.com/modelcontextprotocol/python-sdk/pull/822
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-3qhf
FAQ
What is CVE-2025-53366?
CVE-2025-53366 is a documented vulnerability. The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.9.4, a validation error in the MCP SDK can cause an unhandled exception whe...
How severe is CVE-2025-53366?
CVSS scoring is not yet available for CVE-2025-53366. Check NVD for updates.
Is there a patch for CVE-2025-53366?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.