CVE-2025-64340
6.7 · MEDIUMOverview
CVE-2025-64340 is a medium-severity vulnerability affecting jlowin fastmcp. 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 and patches from jlowin. Update fastmcp to the latest patched version. 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.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| jlowin | fastmcp | >= 0, < 3.2.0 | Affected |
Frequently Asked Questions
What is CVE-2025-64340?
CVE-2025-64340 is a medium-severity vulnerability affecting jlowin fastmcp. 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 and patches from jlowin. Update fastmcp to the latest patched version. 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's AI-powered security agents can automatically detect CVE-2025-64340 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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