How broadly exploitable is this vulnerability?

Exploitability depends on how the OpenAPIProvider is exposed and which operations are available to MCP clients. If a client can invoke operations with attacker-controlled path parameters, they may be able to influence backend request paths and perform SSRF against internal services accessible to the MCP server.

Does an attacker need authentication or special access to exploit this?

Yes, some level of access is required. The attacker must be able to act as an MCP client that can call affected operations and supply crafted path parameter values. The resulting SSRF is "authenticated" in the sense that the MCP server includes its configured authorization headers when contacting backend services.

What is the safest general fix pattern for this issue?

The safest pattern is to treat path parameters as untrusted data, always URL-encode them before interpolation, and validate the final resolved URL against a strict allowlist of hosts and path prefixes. This should be implemented in a central request-building component so that all OpenAPI operations benefit from the same protections.

Severity:

CRITICAL RISK

(10.0)

Server-Side Request Forgery via Path Traversal (CWE-918) in FastMCP OpenAPIProvider URL Construction

CVE-2026-32871

Published:

Apr 2, 2026

Status:

Analyzed

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

Recent Vulnerabilities

CWE-77;CWE-78

CRITICAL RISK

CRITICAL

(9.8)

OS Command Injection (CWE-78) in Totolink A7100RU CGI Handler setAccessDeviceCfg

Remote Code Execution on the Router

April 12, 2026

CWE-77;CWE-78

CRITICAL RISK

CRITICAL

(9.8)

OS Command Injection (CWE-78) in Totolink A7100RU CGI setLedCfg Handler

Remote Code Execution on the Router

April 12, 2026

Vulnerability Type

Category:

Server-Side Request Forgery (SSRF)

CWE:

CWE-918

Impact:

Authenticated Server-Side Request Forgery to Internal Backend Endpoints

Severity:

CRITICAL RISK

(10.0)

CVSS Version:

3.1

Vulnerability Type

Category:

Server-Side Request Forgery (SSRF)

CWE:

CWE-918

Impact:

Authenticated Server-Side Request Forgery to Internal Backend Endpoints

Severity:

CRITICAL RISK

(10.0)

CVSS Version:

3.1

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Ask AI for summary of CodeAnt

Server-Side Request Forgery via Path Traversal (CWE-918) in FastMCP OpenAPIProvider URL Construction

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

CRITICAL RISK

CRITICAL

(9.8)

OS Command Injection (CWE-78) in Totolink A7100RU CGI Handler setAccessDeviceCfg

CRITICAL RISK

CRITICAL

(9.8)

OS Command Injection (CWE-78) in Totolink A7100RU CGI setLedCfg Handler

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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