CVE-2025-53365: MCP Python SDK Denial of Service via Streamable HTTP Transport

# CVE-2025-53365: MCP Python SDK Denial of Service via Streamable HTTP Transport

https://gcdradar.vercel.app/incidents/cve-2025-53365-mcp-python-sdk-denial-of-service-via-streamab · AIR-2025-0304 · closed 2025-07-04

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2025-07-04
- AI role: Attack on AI
- Products: mcp, mcp python sdk
- CVE ids: CVE-2025-53365
- CVSS: 8.7

## Summary

An unhandled exception in the Model Context Protocol Python SDK can cause server crashes during streamable HTTP sessions. Exploitation leads to a denial of service requiring manual service restarts.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2025-07-04: CVE-2025-53365: The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). (https://nvd.nist.gov/vuln/detail/CVE-2025-53365)
- 2025-07-04: CVE-2025-53365: MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service (https://github.com/advisories/GHSA-j975-95f5-7wqh)

## Sources

- 2025-07-04 GitHub Advisory Database: CVE-2025-53365: MCP Python SDK has Unhandled Exception in Streamable HTTP Transport, Leading to Denial of Service https://github.com/advisories/GHSA-j975-95f5-7wqh
- 2025-07-04 NVD: CVE-2025-53365: The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). https://nvd.nist.gov/vuln/detail/CVE-2025-53365

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.