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CVE-2025-64340

6.7 · MEDIUM

FastMCP is the standard framework for building MCP applications.

Published Apr 3, 2026CWE-78EPSS 0.73%

Overview

CVE-2025-64340 is a medium-severity vulnerability. It was published on April 3, 2026 and has a CVSS 3.1 base score of 6.7 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.7, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, server names containing shell metacharacters (e.g., &) can cause command injection on Windows when passed to fastmcp install claude-code or fastmcp install gemini-cli. These install paths use subprocess.run() with a list argument, but on Windows the target CLIs often resolve to .cmd wrappers that are executed through cmd.exe, which interprets metacharacters in the flattened command string. This issue has been patched in version 3.2.0.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/PrefectHQ/fastmcp/pull/3522GitHubgithub.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5gGitHubgithub.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g

How CyberStrike helps

Frequently asked questions

What is CVE-2025-64340?

CVE-2025-64340 is a medium-severity vulnerability. It was published on April 3, 2026 and has a CVSS 3.1 base score of 6.7 (MEDIUM).

How severe is CVE-2025-64340?

This vulnerability has a CVSS 3.1 base score of 6.7, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-64340?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-64340?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-64340 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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