GHSA-j975-95f5-7wqh

MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service

Source: GitHub Advisory Database (reviewed) High CVE-2025-53365

Packages

Ecosystem	Package	Affected	Fixed in
PyPI	mcp	< 1.10.0	1.10.0

Details

As written in the advisory (Markdown source, shown as plain text).

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. Thank you to Rich Harang for reporting this issue.

References

External links from the advisory. They lead to third-party sites.

https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-j975-95f5-7wqh web
https://nvd.nist.gov/vuln/detail/CVE-2025-53365 advisory
https://github.com/modelcontextprotocol/python-sdk/pull/967 web
https://github.com/modelcontextprotocol/python-sdk/commit/7b420656de48cfdb90b39eb582e60b6d55c2f891 web
https://github.com/advisories/GHSA-j975-95f5-7wqh advisory
https://github.com/modelcontextprotocol/python-sdk package
https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.10.0 web
https://github.com/pypa/advisory-database/tree/main/vulns/mcp/PYSEC-2026-1618.yaml web
https://pypi.org/project/mcp web