CVE-2026-14538
Severity CVSS v4.0:
MEDIUM
Type:
CWE-285
Improper Authorization
Publication date:
31/07/2026
Last modified:
31/07/2026
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.
Impact
Base Score 4.0
5.70
Severity 4.0
MEDIUM