Is CVE-2025-53366 in the CISA KEV catalog?

No. CVE-2025-53366 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the EPSS score for CVE-2025-53366?

CVE-2025-53366 has an EPSS score of 5.69% (92th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2025-53366?

No published fix for CVE-2025-53366 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2025-53366

UNSCOREDEPSS 92th pctl

NVD

Description

The MCP Python SDK, called `mcp` on PyPI, is a Python implementation of the Model Context Protocol (MCP). Prior to version 1.9.4, a validation error in the MCP SDK can cause an unhandled exception when processing malformed requests, resulting in service unavailability (500 errors) until manually restarted. Impact may vary depending on the deployment conditions, and presence of infrastructure-level resilience measures. Version 1.9.4 contains a patch for the issue.

CWE-248

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3.1 Vector

No CVSS vector data available.

Exploit Intelligence

5.69%probability of exploitation in 30 days

92ndpercentile

High risk: more likely to be exploited than 92% of all known CVEs.

References

Other references3

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-07-08.