CVE-2026-32871

[CVE catalog]

Severity

Critical · CVSS 10CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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

Published

Apr 2, 2026, 2:52:39 PM UTC

Source

[NVD] · [CVE record]

EPSS

0.91% · Oct 25, 2026

A flaw was found in FastMCP. An authenticated attacker can exploit a path traversal vulnerability in the _build_url() method of the RequestDirector class. By manipulating path parameters in an OpenAPI operation, an attacker can use directory traversal sequences (../) to bypass the intended API prefix. This allows the attacker to access arbitrary backend endpoints, leading to authenticated Server-Side Request Forgery (SSRF). Server-Side Request Forgery (SSRF) enables an attacker to compel the server-side application to send HTTP requests to an arbitrary domain. fastmcp: FastMCP: Authenticated Server-Side Request Forgery via path traversal in OpenAPI path parameters This is an Important severity flaw affecting FastMCP, which is utilized in Red Hat OpenShift AI, Red Hat Satellite, Hosted OpenShift Clusters, and Ansible Services. An authenticated attacker can exploit a path traversal vulnerability in FastMCP's OpenAPI path parameter handling to achieve Server-Side Request Forgery (SSRF), allowing access to arbitrary backend endpoints. As a result of a successful exploitation of this vulnerability the attacker may be able to access private endpoints, exfiltrate data, achieving privilege escalation or by-pass security controls within the affected component. The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.