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How the CVE Works:
The vulnerability occurs in MCP Python SDK’s Streamable HTTP Transport when processing client requests. During streamed HTTP sessions, if a malicious client deliberately triggers an exception (like connection termination) after establishing the session, the server fails to handle the `ClosedResourceError` exception. This uncaught exception propagates to the main event loop, crashing the server process. The lack of proper exception handling in the streaming component allows a single malicious request to disrupt service availability, requiring manual intervention to restart the affected instance.
DailyCVE Form:
Platform: MCP Python SDK
Version: <1.7.4
Vulnerability: Unhandled Exception
Severity: High
Date: 2025-07-04
Prediction: Patch by 2025-07-18
What Undercode Say:
Crash reproduction import requests from contextlib import suppress with suppress(Exception): requests.post(stream_url, data=malformed_payload) Debugging command strace -f -e trace=network python3 mcp_server.py
How Exploit:
1. Establish valid HTTP streaming session
2. Abruptly terminate connection mid-stream
3. Server crashes with `ClosedResourceError`
Protection from this CVE:
- Update to MCP Python SDK β₯1.7.4
- Implement process supervision
- Add custom exception middleware
Impact:
- Service disruption
- Manual recovery required
- No data compromise
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
