CVE-2026-32871
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Description
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.
Statement
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.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Additional information
- This content is not included.Bugzilla 2454434: fastmcp: FastMCP: Authenticated Server-Side Request Forgery via path traversal in OpenAPI path parameters
- Content from cwe.mitre.org is not included.CWE-918: Server-Side Request Forgery (SSRF)
External References
Content from www.cve.org is not included.https://www.cve.org/CVERecord?id=CVE-2026-32871
Content from nvd.nist.gov is not included.https://nvd.nist.gov/vuln/detail/CVE-2026-32871
Content from github.com is not included.https://github.com/PrefectHQ/fastmcp/pull/3507
Content from github.com is not included.https://github.com/PrefectHQ/fastmcp/releases/tag/v3.2.0
Affected Packages and Issued Red Hat Security Errata
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.
| Products / Services | Components | State | Errata |
|---|---|---|---|
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-mlflow-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-datascience-cpu-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-minimal-cpu-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-pytorch-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-pytorch-rocm-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-tensorflow-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-pipeline-runtime-tensorflow-rocm-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-codeserver-datascience-cpu-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-datascience-cpu-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-pytorch-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-pytorch-rocm-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-tensorflow-cuda-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-tensorflow-rocm-py312-rhel9 | Not affected | |
| Red Hat OpenShift AI (RHOAI) | rhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9 | Not affected | |
| Red Hat Satellite 6.18 | satellite/foreman-mcp-server-rhel9 | Fixed | RHSA-2026:36350 |
Common Vulnerability Scoring System (CVSS) Score Details
Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authorities (CNA) source for its products and services (see Red Hat classifications ).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| CVSS v3 Base Score | 8.5 | 10 | 8.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | High |
| Privileges Required | Low | None | Low |
| User Interaction | None | None | None |
| Scope | Changed | Changed | Changed |
| Confidentiality Impact | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
CVSS v3 Vector
Red Hat CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
cve.org CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
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My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
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- "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.
What can I do if my product is listed as "Will not fix"?
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- Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
- Apply a mitigation (if one exists).
- Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
What can I do if my product is listed as "Fix deferred"?
Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
- Apply a mitigation (if one exists).
- Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
- Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.
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