An authenticated authorization bypass vulnerability exists in MCP Toolbox for Databases due to missing scope enforcement across older protocol handlers. While the 2025-11-25 protocol version handler correctly enforces per-tool restrictions defined by scopesRequired, older supported protocol versions (2025-06-18, 2025-03-26, and 2024-11-05) omit this check. An authenticated client with low-privilege tokens (e.g., read) can bypass the intended per-tool scope restrictions and execute high-privilege tools (e.g., admin) simply by specifying an older protocol version in the MCP-Protocol-Version header, or by omitting the header entirely (which causes the server to default to the vulnerable 2024-11-05 handler).
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/googleapis/mcp-toolbox/pull/3049 Patch
- https://github.com/googleapis/mcp-toolbox/pull/3335 Patch
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 8.6 · googleNVD modified 2026-10-26 11:10
Affected (CPE criteria) 1
cpe:2.3:a:google:mcp_toolbox_for_databases:1.3.0:*:*:*:*:*:*:*