CVE-2026-14540: Server-Side Request Forgery via Unrestricted HTTP Redirection in MCP Toolbox

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-31 · updated 2026-10-23
Weakness: CWE-918

Description

A Server-Side Request Forgery (SSRF) vulnerability exists in the generic HTTP source and tool components of Google mcp-toolbox versions 0.3.0 through 1.4.0. While the toolbox implements baseline input sanitization for user-controlled parameters, the underlying HTTP client (internal/sources/http/http.go) fails to safely regulate request redirection boundaries. Specifically, the client is initialized without a restrictive CheckRedirect policy hook and lacks target IP validation. An attacker or a malicious data-driven prompt can supply a crafted path parameter that triggers an open redirect or a direct destination swap on the target backend, coercing the mcp-toolbox into blindly following the redirection and making unauthorized requests to internal or arbitrary external endpoints.

Affected products

Google MCP Toolbox for Databases (googleapis/mcp-toolbox): from 0.3.0 before 1.5.0 — fixed in 1.5.0

How to fix

Upgrade to a fixed version: Google MCP Toolbox for Databases (googleapis/mcp-toolbox) 1.5.0. Check the vendor advisory for mitigations.

References

https://github.com/googleapis/mcp-toolbox/pull/3448

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