CVE-2025-53366

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.

PUBLISHED Reserved 2025-06-27 | Published 2025-07-04 | Updated 2025-07-08 | Assigner GitHub_M

Problem types

CWE-248: Uncaught Exception

Product status

References

github.com/...on-sdk/security/advisories/GHSA-3qhf-m339-9g5v

github.com/modelcontextprotocol/python-sdk/pull/822

github.com/...ommit/29c69e6a47d0104d0afcea6ac35e7ab02fde809a

cve.org (CVE-2025-53366)

nvd.nist.gov (CVE-2025-53366)

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