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How the CVE Works:
The vulnerability (CVE-2025-XXXXX) in the MCP Python SDK arises due to improper input validation in the FastMCP Server component. When malformed requests are processed, the SDK fails to handle exceptions correctly, triggering an unhandled error condition. This causes the server to return HTTP 500 errors, rendering it unresponsive until a manual restart is performed. The issue stems from insufficient sanitization of user-supplied data before processing, allowing crafted payloads to disrupt service availability.
DailyCVE Form:
Platform: MCP Python SDK
Version: FastMCP Server (affected)
Vulnerability: Unhandled Exception (DoS)
Severity: High
Date: Jul 4, 2025
Prediction: Patch expected by Jul 18, 2025
What Undercode Say:
Check server logs for 500 errors
grep "500" /var/log/fastmcp/error.log
Test payload triggering the issue
curl -X POST http://target/api -d '{"malformed":"data"}'
Mitigation workaround (restart service)
systemctl restart fastmcp-server
How Exploit:
Craft malformed API requests to trigger unhandled exceptions, causing service disruption. Repeated exploitation leads to sustained DoS.
Protection from this CVE:
- Apply patch upon release.
- Implement request sanitization.
- Use rate-limiting.
Impact:
Service unavailability until manual intervention.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
