CVE-2026-14541
Authentication Bypass and Audience Confusion in MCP Toolbox OAuth Provider
- State
- Published
- Severity
- 8.0 High
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Reserved
- Jul 3, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.0 High | CVSS: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 |
Weaknesses
- CWE-287 (Improper Authentication)
Affected Products
| Product | Versions |
|---|---|
mcp-toolboxGoogle |
|
References
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