high8.7
CVE-2025-53365
MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | mcp | < 1.10.0 | 1.10.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/modelcontextprotocol/python-sdk/commit/7b420656de48cfdb90b39eb582e60b6d55c2f891
- https://github.com/modelcontextprotocol/python-sdk/pull/967
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-j975-95f5-7wqh
- https://github.com/advisories/GHSA-j975-95f5-7wqh
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.10.0
- https://nvd.nist.gov/vuln/detail/CVE-2025-53365
- https://github.com/modelcontextprotocol/python-sdk
- https://github.com/pypa/advisory-database/tree/main/vulns/mcp/PYSEC-2026-1618.yaml
- https://pypi.org/project/mcp