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.

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact High

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00202.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Google mcp-toolbox unaffected
Version Status Constraints
0.16.1 affected ≤ 1.4.0

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/googleapis/mcp-toolbox/pull/3452 cve-icon
History

Fri, 31 Jul 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Fri, 31 Jul 2026 02:00:00 +0000

Type Values Removed Values Added
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.
Title BigQuery Dataset Allowlist Bypass via Metadata Dry-Run in MCP Toolbox
Weaknesses CWE-285
CWE-863
References
Metrics cvssV4_0

{'score': 5.7, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Google

Published:

Updated: 2026-07-31T16:09:31.250Z

Reserved: 2026-07-03T02:06:17.583Z

Link: CVE-2026-14538

cve-icon Vulnrichment

Updated: 2026-07-31T16:09:23.644Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T19:15:18Z

Weaknesses