FastMCP updated to MCP 1.23+ due to CVE-2025-66416
FastMCP versions from 2.12.3 up to but not including 2.14.0 allowed usage of vulnerable MCP SDK versions prior to 1.23, which are affected by CVE-2025-66416. FastMCP itself does not directly use the vulnerable components, but the underlying MCP SDK versions could be vulnerable. Users are advised to upgrade to FastMCP 2.14.0 or later, which requires MCP SDK 1.23 or newer, mitigating the vulnerability.
AI Analysis
Technical Summary
CVE-2025-66416 affects MCP SDK versions prior to 1.23. FastMCP versions >=2.12.3 and <2.14.0 permitted use of these vulnerable MCP SDK versions. Although FastMCP does not directly use the affected MCP SDK components, the dependency on vulnerable MCP SDK versions exposes users to the CVE. FastMCP 2.14.0 and later require MCP SDK 1.23 or newer, which addresses the vulnerability.
Potential Impact
The impact arises from FastMCP allowing usage of MCP SDK versions vulnerable to CVE-2025-66416. While FastMCP itself does not directly use the vulnerable components, the underlying vulnerable SDK could expose users to the associated risks of CVE-2025-66416. No known exploits in the wild have been reported.
Mitigation Recommendations
Users should upgrade FastMCP to version 2.14.0 or later, which mandates MCP SDK 1.23 or newer, thereby mitigating the vulnerability. A patch is available in FastMCP 2.14.0. No additional mitigation actions are indicated.
FastMCP updated to MCP 1.23+ due to CVE-2025-66416
Description
FastMCP versions from 2.12.3 up to but not including 2.14.0 allowed usage of vulnerable MCP SDK versions prior to 1.23, which are affected by CVE-2025-66416. FastMCP itself does not directly use the vulnerable components, but the underlying MCP SDK versions could be vulnerable. Users are advised to upgrade to FastMCP 2.14.0 or later, which requires MCP SDK 1.23 or newer, mitigating the vulnerability.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2025-66416 affects MCP SDK versions prior to 1.23. FastMCP versions >=2.12.3 and <2.14.0 permitted use of these vulnerable MCP SDK versions. Although FastMCP does not directly use the affected MCP SDK components, the dependency on vulnerable MCP SDK versions exposes users to the CVE. FastMCP 2.14.0 and later require MCP SDK 1.23 or newer, which addresses the vulnerability.
Potential Impact
The impact arises from FastMCP allowing usage of MCP SDK versions vulnerable to CVE-2025-66416. While FastMCP itself does not directly use the vulnerable components, the underlying vulnerable SDK could expose users to the associated risks of CVE-2025-66416. No known exploits in the wild have been reported.
Mitigation Recommendations
Users should upgrade FastMCP to version 2.14.0 or later, which mandates MCP SDK 1.23 or newer, thereby mitigating the vulnerability. A patch is available in FastMCP 2.14.0. No additional mitigation actions are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- BREW-fastmcp-GHSA-rcfx-77hg-w2wv
- Osv Schema Version
- 1.7.3
- Ecosystems
- ["Homebrew"]
Threat ID: 6aac8e6955bf5e2cf5491ea0
Added to database: 09/18/2026, 01:05:45 UTC
Last enriched: 09/18/2026, 01:55:48 UTC
Last updated: 09/18/2026, 02:01:24 UTC
Views: 6
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