MCP Toolbox for Databases vulnerable to DNS rebinding attacks

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

9.4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-9739: 0.28% estimated exploitation activity in the next 30 days; percentile 20.46 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

28 May 2026, 00:30 UTC

Last modified by the source

1 Jul 2026, 20:54 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7pf3-8xx7-rvhf

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# Patch Next advisory brief: CVE-2026-9739

Advisory: MCP Toolbox for Databases vulnerable to DNS rebinding attacks
IDs: CVE-2026-9739, GHSA-7pf3-8xx7-rvhf
Record: https://patchnext.com/advisories/cve-2026-9739 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/googleapis/mcp-toolbox 1.2.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/googleapis/mcp-toolbox: affected < 1.2.0; fixed in 1.2.0

## Suggested inspection (read-only)
- Go github.com/googleapis/mcp-toolbox: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/googleapis/mcp-toolbox.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7pf3-8xx7-rvhf (GitHub-reviewed advisory GHSA-7pf3-8xx7-rvhf lists affected ranges: Go github.com/googleapis/mcp-toolbox >=0 <1.2.0)

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