TI-2026-25332 Aliases CVE-2026-32871 GHSA-vv7q-7jx5-f767

FastMCP OpenAPI Provider has an SSRF & Path Traversal Vulnerability

HIGH 82CWE-918Published 2026-04-02 · Updated 2026-07-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: —
Confidentiality · integrity · availability: High · High · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.

Summary

FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability exists in the _build_url() method. When an OpenAPI operation defines path parameters (e.g., /api/v1/users/{user_id}), the system directly substitutes parameter values into the URL template string without URL-encoding. Subsequently, urllib.parse.urljoin() resolves the final URL. Since urljoin() interprets ../ sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in authenticated SSRF, as requests are sent with the authorization headers configured in the MCP provider. This issue has been patched in version 3.2.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00925 60th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed fastmcp (PrefectHQ): 3.2.0fastmcp (PyPI): 3.2.0Red Hat: 1 advisory

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
PrefectHQ	fastmcp	before 3.2.0	3.2.0	Patch available	CNA
—	fastmcp (PyPI)	before 3.2.0	3.2.0	Patch available	GHSA-vv7q-7jx5-f767

fastmcp VendorPrefectHQ Affected before 3.2.0 Fixed in 3.2.0 Patch available CNA
fastmcp (PyPI) Vendor— Affected before 3.2.0 Fixed in 3.2.0 Patch available GHSA-vv7q-7jx5-f767

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:jlowin:fastmcp::::::::	before 3.2.0	Vulnerable	jlowin

cpe:2.3:a:jlowin:fastmcp:*:*:*:*:*:*:*:* Versions before 3.2.0 Vulnerable ·jlowin

Remediation

Fix · CNA fastmcp (PrefectHQ) Fixed in 3.2.0
Fix · GHSA-vv7q-7jx5-f767 fastmcp (PyPI) Fixed in 3.2.0 Advisory →

Red Hat 1 advisory

RHSA-2026:36350 Released 2026-07-07 · Red Hat rating Important
satellite/foreman-mcp-server-rhel9 container image available as a Technology Preview
- Red Hat Satellite 6.18 registry.redhat.io/satellite/foreman-mcp-server-rhel9

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Satellite 6.18	Fixed	RHSA-2026:36350

Not affected: 1 product

Red Hat OpenShift AI (RHOAI)

Timeline

2026-10-02 Threatist record created from CVE-2026-32871
2026-10-03 Alias added: GHSA-vv7q-7jx5-f767

References

Exploit 1

https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-vv7q-7jx5-f767

Patch 2

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-32871

Other 8

TI-2026-04695 Git Argument Injection in prefecthq/prefect CVSS 3.0CRITICAL 9.9
TI-2026-03027 Authentication Bypass in prefecthq/prefect CVSS 3.0HIGH 7.5
TI-2026-06805 PrefectHQ prefect WebSocket Endpoint in missing authentication CVSS 4.0MEDIUM 6.9
TI-2026-06804 PrefectHQ prefect Health Check API health endswith improper authentication CVSS 4.0MEDIUM 6.9
TI-2024-07590 CORS Misconfiguration in prefecthq/prefect CVSS 3.0HIGH 7.6
TI-2026-06807 PrefectHQ prefect GitRepository Pull storage.py argument injection CVSS 4.0MEDIUM 5.3

See all 11 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences