GitHub Advisoryadvisory · PyPI
GHSA-j975-95f5-7wqh MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service
HIGH
Official page ↗
- Aliases
- CVE-2025-53365
- Ecosystem
- PyPI
- Packages
- mcp
- Severity
- High
- CVSS vector
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Weaknesses
- CWE-248
- Reviewed
- 2025-07-04
Affected packages
• PyPI mcp: < 1.10.0 → fixed in 1.10.0
Description
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.
Related
Alias · CVE (1)
- CVE-2025-53365 The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). vulnerability
Weakness · CWE (1)
- CWE-248 Uncaught Exception weakness
References
- 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