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CVE-2026-14538— BigQuery Dataset Allowlist Bypass via Metadata Dry-Run in MCP Toolbox

Quick assessment

Affected
Google mcp-toolbox
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Google MCP Toolbox for Databases是美国Google公司的数据库管理工具。 Google MCP Toolbox for Databases 0.16.1版本至1.4.0版本存在授权问题漏洞，该漏洞源于bigquery-execute-sql工具组件存在授权和边界绕过缺陷，依赖BigQuery dry-run API强制执行数据集限制，但fail-open逻辑缺陷导致API返回空数组时绕过allowedDatasets验证，从而可能导致攻击者提取明确排除数据集的DDL结构模式

CVSS 5.7 · Medium EPSS 0.20% · P10

Affected Version Matrix 1

VendorProduct Version RangeStatus
Google mcp-toolbox 0.16.1≤ 1.4.0 affected
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I. Basic Information for CVE-2026-14538

Vulnerability Information
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Vulnerability Title
BigQuery Dataset Allowlist Bypass via Metadata Dry-Run in MCP Toolbox
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:U
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Google MCP Toolbox for Databases 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Google MCP Toolbox for Databases是美国Google公司的数据库管理工具。 Google MCP Toolbox for Databases 0.16.1版本至1.4.0版本存在授权问题漏洞，该漏洞源于bigquery-execute-sql工具组件存在授权和边界绕过缺陷，依赖BigQuery dry-run API强制执行数据集限制，但fail-open逻辑缺陷导致API返回空数组时绕过allowedDatasets验证，从而可能导致攻击者提取明确排除数据集的DDL结构模式
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Google mcp-toolbox 0.16.1 ~ 1.4.0 -

II. Public POCs for CVE-2026-14538

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III. Intelligence Information for CVE-2026-14538

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Patches & Fixes for CVE-2026-14538 (1)

Same Patch Batch · Google · 2026-07-31 · 5 CVEs total

CVE-2026-14537 8.1 HIGH Authorization Bypass in MCP Toolbox Legacy HTTP Endpoints
CVE-2026-14540 8.0 HIGH Server-Side Request Forgery via Unrestricted HTTP Redirection in MCP Toolbox
CVE-2026-14541 8.0 HIGH Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider
CVE-2026-14539 6.6 MEDIUM Denial of Service via Unrestricted Payload Buffering in MCP Toolbox

IV. Related Vulnerabilities

Same product: mcp-toolbox
Same vendor: Google
Same weakness: CWE-285

V. Comments for CVE-2026-14538

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