CVE-2026-14541
Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider
CVSS Score
0.0
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-287 |
| Vendor | |
| Product | mcp-toolbox |
| Ecosystems | |
| Industries | Technology |
| Published | Jul 31, 2026 |
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Affected Versions
Google / mcp-toolbox
1.4.0
References
Credits
HE WEI (ギカク)