Vulnerability Description
An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When verifying an unparsed opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), the toolbox decodes the response into an introspectResp struct where the Active field is declared as a pointer to a boolean (*bool). The code only explicitly rejects a token if the response contains a populated active field set to false (if introspectResp.Active != nil && !*introspectResp.Active). If an introspection endpoint responds with a payload that completely omits the mandatory active key, the internal variable remains nil, causing the conditional check to short-circuit. As a result, Toolbox accepts authorization tokens missing the "active" field, granting access to protected tools and underlying data sources.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mcp Toolbox For Databases | >= 1.0.0, <= 1.3.0 |
Related Weaknesses (CWE)
References
- https://github.com/googleapis/mcp-toolbox/pull/3341PatchThird Party Advisory
FAQ
What is CVE-2026-11717?
CVE-2026-11717 is a vulnerability with a CVSS score of 9.1 (CRITICAL). An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When verifying an unparsed opaque token via an OAuth 2.0 int...
How severe is CVE-2026-11717?
CVE-2026-11717 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-11717?
Check the references section above for vendor advisories and patch information. Affected products include: Google Mcp Toolbox For Databases.