CVE-2026-14541

An authentication bypass and audience confusion vulnerability exists in the Google OAuth provider component of Google mcp-toolbox version 1.4.0. When a Google authService is initialized with mcpEnabled: true but lacks an explicitly defined audience or clientId, the ValidateMCPAuth pipeline for opaque tokens skips audience validation entirely. As a result, the toolbox will accept any valid Google OAuth access token—even those minted for unrelated ecosystem applications—granting unauthorized clients access to protected tools and data backends.

CVSS 4.0

8.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 16% of CVEs (scores of 2026-10-25)

CWE

CWE-287

Published

2026-07-31

Modified

2026-10-23

Record from

the NVD, synced 2026-10-24

Affected

• google:mcp_toolbox_for_databases

References

• https://github.com/googleapis/mcp-toolbox/pull/3450

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