FastMCP OAuth Proxy token reuse across MCP servers (jlowin fastmcp)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.37 % · percentile 31 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Modified
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.
Weaknesses (CWE)
References
- https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-5h2m-4q8j-pqpj
- https://access.redhat.com/security/cve/CVE-2025-69196
- https://bugzilla.redhat.com/show_bug.cgi?id=2448179
- https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-69196.json
- https://access.redhat.com/errata/RHSA-2026:36350
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | HIGH 7.4 | CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N | GitHub_M |
| CVSS 3.1 | HIGH 7.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N | redhat-SADP |
| CVSS 4.0 | HIGH 7.4 | CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N | NVD · nvd@nist.gov (Primary) |
| CVSS 3.1 | HIGH 7.4 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N | NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary) |
Advisories
- GHSA-5h2m-4q8j-pqpj — FastMCP OAuth Proxy token reuse across MCP servers
- PYSEC-2026-2474 — FastMCP OAuth Proxy token reuse across MCP servers
European references
- ENISA EUVD · EUVD-2025-208759
- GCVE · GCVE-0-2025-69196
Affected configurations (NVD CPE)
cpe:2.3:a:jlowin:fastmcp:*:*:*:*:*:*:*:*< 2.14.2
Affected products
| Product | Versions |
|---|---|
| jlowin · fastmcp | affected < 2.14.2 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |