CVE-2026-14538

Name of the Vulnerable Software and Affected Versions Google mcp-toolbox versions 0.16.1 through 1.4.0

Description An improper authorization and security-boundary bypass exists in the bigquery-execute-sql tool component. The system uses the BigQuery dry-run API to enforce dataset restrictions; however, a fail-open logic flaw occurs when the API returns an empty array for specialized constructs, allowing authenticated attackers to bypass allowedDatasets validation checks. This enables the extraction of structural DDL (Data Definition Language) schemas for excluded datasets through INFORMATION SCHEMA and provides access to downstream federated row data via EXTERNAL QUERY connections.

Recommendations Update Google mcp-toolbox to a version later than 1.4.0.