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CVE-2025-69196

FastMCP OAuth Proxy token reuse across MCP servers

Published: Mar 16, 2026Updated: Jul 15, 2026 Sources: CVE List NVD GHSACWE-863
6.5MEDIUM
NVD MITRE
EPSS Score
0.4%
Top 71.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:UC:HI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:NIntegrity
None
A:NAvailability
None
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Weaknesses

CWE-863CWE-1220

Affected Products

jlowin
individual-devaka fastmcp
fastmcpLibrary
AI / ML / ai-agent-tooling
PyPI
package-ecosystem
fastmcp
OSS Libraries

Exploitability

Official Patch Available
Workaround Available

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Initial Access
View detailed technique mapping

References

https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-5h2m-4q8j-pqpj
github.com
https://nvd.nist.gov/vuln/detail/CVE-2025-69196
nvd.nist.gov
https://github.com/PrefectHQ/fastmcp
github.com
and 4 more references View all →

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