Hi,

The following vulnerability was published for python-mcp.

CVE-2026-59951[0]:
| The MCP Python SDK, called mcp on PyPI, is a Python implementation
| of the Model Context Protocol (MCP). From 1.8.0 until 1.30.0 and
| 2.2.0, stateful Streamable HTTP servers, including FastMCP,
| MCPServer, Server.streamable_http_app(), and
| StreamableHTTPSessionManager, retain session entries without an idle
| expiration or aggregate session-count limit. DELETE, refused opening
| requests, and completed sessions do not reliably discard their
| entries, and each entry can retain parsed initialize parameters. A
| client that can reach the endpoint can therefore create ordinary
| short requests that grow server memory without bound until restart.
| Stateless HTTP, stdio, and SSE transports are not affected. This
| issue is fixed in versions 1.30.0 and 2.2.0.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-59951
https://www.cve.org/CVERecord?id=CVE-2026-59951
[1] https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-84m7-p3x7-pcfv
[2] https://github.com/modelcontextprotocol/python-sdk/pull/3395
[3] https://github.com/modelcontextprotocol/python-sdk/pull/3426
[4] https://github.com/modelcontextprotocol/python-sdk/commit/92120b4b0f50385af096592d7cee932fc1d994e7

Regards,
Salvatore