CVE-2026-9739: MCP Toolbox for Databases vulnerable to DNS rebinding attacks

May 28, 2026 (updated July 1, 2026)

Vulnerable to DNS rebinding attacks when using SSE (http://b/499408790). During the beta phase, we implemented allowed-origins and allowed-hosts flags to align with MCP security guidelines. However, the hardcoded Access-Control-Allow-Origin: * header in the SSE initialization handler was inadvertently retained. This vulnerability specifically impacts users connecting via Toolbox using SSE under specification v2024-11-05.

References

github.com/advisories/GHSA-7pf3-8xx7-rvhf
github.com/googleapis/mcp-toolbox/commit/c4c7bd917e686de68e2be866cfe3872c3439efae
github.com/googleapis/mcp-toolbox/issues/3053
github.com/googleapis/mcp-toolbox/pull/3054
nvd.nist.gov/vuln/detail/CVE-2026-9739

Code Behaviors & Features

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