FKIE_CVE-2025-64340

Vulnerability from fkie_nvd - Published: 2026-04-03 16:16 - Updated: 2026-04-21 01:09
Severity ?
6.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
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.
References
security-advisories@github.comhttps://github.com/PrefectHQ/fastmcp/pull/3522Issue Tracking, Patch
security-advisories@github.comhttps://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5gExploit, Patch, Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5gExploit, Patch, Vendor Advisory
Impacted products
Vendor Product Version
jlowin fastmcp *
To clipboard 

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      "value": "FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, server names containing shell metacharacters (e.g., \u0026) 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."
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  "id": "CVE-2025-64340",
  "lastModified": "2026-04-21T01:09:14.960",
  "metrics": {
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          "availabilityImpact": "HIGH",
          "baseScore": 6.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H",
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        "Patch"
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      "url": "https://github.com/PrefectHQ/fastmcp/pull/3522"
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.