---
id: CVE-2026-14538
title: >-
  An improper authorization and security-boundary bypass vulnerability in the
  bigquery-execute-sql tool component of Google mcp-toolbox versions 0.16.1
  through 1.4.0 allows an authenticated attacker to bypass allowedDatasets
  validation che…
summary: >-
  An improper authorization and security-boundary bypass vulnerability in the
  bigquery-execute-sql tool component of Google mcp-toolbox versions 0.16.1
  through 1.4.0 allows an authenticated attacker to bypass allowedDatasets
  validation che…
severity: high
cvss: 7.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N'
cwe:
  - CWE-285
  - CWE-863
vendor: google
product: mcp_toolbox_for_databases
affected:
  - 'mcp_toolbox_for_databases >= 0.16.1, <= 1.4.0'
published: '2026-07-31'
updated: '2026-08-08'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-14538'
references:
  - url: 'https://github.com/googleapis/mcp-toolbox/pull/3452'
    label: cve-coordination@google.com
tags:
  - nvd
epss: 0.00204
epssPercentile: 0.09262
ingestedAt: '2026-08-08T14:22:57.143Z'
---

## Overview

An improper authorization and security-boundary bypass vulnerability in the bigquery-execute-sql tool component of Google mcp-toolbox versions 0.16.1 through 1.4.0 allows an authenticated attacker to bypass allowedDatasets validation checks. The toolbox relies on the BigQuery dry-run API to enforce dataset restrictions, but due to a fail-open logic flaw, it bypasses validation when the API returns an empty array for specialized constructs. This allows the attacker to extract structural DDL schemas for explicitly excluded datasets via INFORMATION_SCHEMA, and access downstream federated row data via EXTERNAL_QUERY connections.

## Affected

- `mcp_toolbox_for_databases >= 0.16.1, <= 1.4.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.