AEGLIX vulnerability intelligence
CVE-2026-32871
CRITICAL · CVSS 10.0 · Modified
Published: 2026-04-02 · Updated: 2026-10-26 · Source: NVD
Stored catalog record
Source record retrieved 2026-10-28T10:18:34.829289+00:00. Scheduled imports handle updates; this page does not assert that the provider was queried just now.
Vulnerability overview
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.
Patch review priority
Critical technical severity
- CVSS is at least 9.0; exploitation is not established by severity alone.
FIRST EPSS: 0.91% · percentile 59.8 · score date 2026-10-27.
EPSS estimates probability of exploitation in the next 30 days. It does not measure your exposure or prove exploitation. The elevated threshold is 10%; CISA KEV takes precedence. About FIRST EPSS ↗
Severity and scoring
- CVSS score
- 10.0 · CRITICAL
- CVSS version
- 4.0
- CVSS vector
- CVSS: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
- Weaknesses
- CWE-918
CVSS measures technical severity; it does not establish whether this vulnerability is being exploited in your environment.
Known exploitation and remediation
Not listed in the CISA catalog retrieved for this record. This does not establish that exploitation has not occurred.
Verify affected versions and patch availability in the vendor advisory before making changes.
Affected products and versions
cpe:2.3:a:jlowin:fastmcp:*:*:*:*:*:*:*:*
Before (exclusive): 3.2.0
These are NVD CPE applicability entries. Some products depend on configuration conditions; consult the official record to confirm applicability.
Advisories and references
- https://github.com/PrefectHQ/fastmcp/commit/40bdfb6b1de0ce30609ee9ba5bb95ecd04a9fb71
Patch
- https://github.com/PrefectHQ/fastmcp/pull/3507
Issue Tracking · Patch
- https://github.com/PrefectHQ/fastmcp/releases/tag/v3.2.0
Product · Release Notes
- https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-vv7q-7jx5-f767
Exploit · Mitigation · Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:36350
- https://access.redhat.com/security/cve/CVE-2026-32871
- https://bugzilla.redhat.com/show_bug.cgi?id=2454434
- https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-vv7q-7jx5-f767
Exploit · Mitigation · Vendor Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-32871.json