CVE-2026-11718: Google MCP Toolbox for Databases (googleapis/mcp-toolbox) · Improper Authentication
Affects Google MCP Toolbox for Databases (googleapis/mcp-toolbox)Source CVE Database V5
Not known to be exploited · CVSS 9.3 Critical.
Data as of 1 Nov 2026, 08:20 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 18 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| GoogleMCP Toolbox for Databases (googleapis/mcp-toolbox) | Affected
| Fixed in– |
GitHubgoogleapis/mcp-toolboxpkg:github/googleapis/mcp-toolboxOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Users should monitor the vendor's advisory channels for updates. Until a fix is released, avoid using version 1.0.0 in production environments or implement additional external token validation controls to verify the issuer field explicitly.
Description
An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When the toolbox validates an opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), it decodes the response into an introspectResp struct. However, the subsequent claim-checking logic (validateClaims) evaluates the issuer condition as if a.issuer != "" && iss != "". If the external OAuth provider's introspection response omits the optional iss (issuer) field completely, the variable iss defaults to an empty string. This causes the conditional block to evaluate to false and be skipped silently. Consequently, the application accepts tokens issued by unauthorized or unintended third-party identity providers.