Description
FastMCP is the standard framework for building MCP applications. Prior to version 2.14.2, the server does not properly respect the resource parameter submitted by the client in the authorization and token request. Instead of issuing the token explicitly for the MCP server, the token is issued for the base_url passed to the OAuthProxy during initialization. This issue has been patched 2.14.2.
References (1)
Core 1
Core References
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https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-5h2m-4q8j-pqpj
Scores
CVSS v3
6.5
EPSS
0.0028
EPSS Percentile
19.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-863
Status
published
Products (2)
jlowin/fastmcp
< 2.14.2 (2 CPE variants)
pypi/fastmcp
0 - 2.14.2PyPI
Published
Mar 16, 2026
Tracked Since
Mar 17, 2026